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HP Integrity Virtual Machines A.03.00: Installation, Configuration, and Administration > Chapter 7 Creating Virtual Storage Devices

Configuring Integrity VM Storage

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This section describes how to plan and set up Integrity VM storage, including:

Integrity VM Storage Considerations

When you configure storage for a virtual machine, consider the following:

The following sections explain each of these considerations.

VM Storage Supportability

Before you configure virtual machine storage, make sure the VM Host storage can be supported by the virtual machine.

  • All VM Host storage available for use by a VM must meet support requirements for the Integrity server and OS version that comprise the VM Host. If the physical storage is not supported by the VM Host, it is not supported for use by a virtual machine.

  • All VM Host storage available for use by a VM must be connected with one of the following adapter and driver types:

    • Fibre Channel adapters supported by the TD driver

    • Fibre Channel adapters supported by the FCD driver

    • SCSI adapters supported by the C8xx driver

    • SCSI adapters supported by the MPT driver

    • SCSI adapters supported by the CISS driver

    • IDE adapters supported by the SIDE driver

    • USB adapters supported by the UsbScsiAdaptor driver (virtual devices only — see Section : “Virtual Devices”)

    • SAS adapters supported by the SASD driver

    • iSCSI adapters supported by the ISCSI driver

    If the physical storage is not connected with one of above adapter and driver types, it cannot be used by a virtual machine. Use the ioscan command to display the VM Host storage that is connected to adapters and drivers.

  • Any VM Host attachable devices available for use by a virtual machine must be supported by the guest OS it is attached to. If the physical device is not supported by the guest OS, the device cannot be attached to the virtual machine.

Performance of Virtual Devices

To meet the performance requirements of applications running in guests, consider the potential performance of each type of Integrity VM storage device.

Different types of virtual media have different effects on the performance of the virtual device because they communicate differently with the VM Host to complete virtual machine I/O operations. To understand the effect of the virtual device type on potential performance, consider the Integrity VM storage I/O stack illustrated in Figure 7-1.

Figure 7-1 Integrity VM Storage IO Stack

Integrity VM Storage IO Stack

For a virtual I/O operation to be completed, it has to travel round trip between the virtual storage adapter and the VM Host physical storage device. The longer the path is, the longer it takes for virtual I/O to be completed. As shown in Figure 7-1, a virtual I/O operation must traverse each software layer in order, from where it originates to the physical media. For example, a virtual I/O operation for a Virtual FileDisk must traverse any logical volume managers the file system is on and the disk drivers that control the whole disk. Therefore, in general, the higher the virtual media is in the VM Host I/O stack, the slower it operates.

The simplified I/O stack in Figure 7-1 does not completely illustrate all the choices that can affect the performance:

  • Performance of different software layers differs.

  • The interfaces to each software layer are different, allowing Integrity VM different ways to send I/O through the layers. For example, whole disks can achieve higher throughput rates than logical volumes and file systems.

  • The I/O layer might have features to help performance increase beyond a lower layer. For example, a file system's buffer cache may help a Virtual FileDisk perform better on some I/O workloads than the other virtual device types, which have no such caching.

For further information on tuning performance at each software layer on the VM Host, see the Integrity VM white papers on http://docs.hp.com.

When you configure virtual devices, consider how the virtual media maps to the physical storage. All virtual media connects to a piece of physical media somewhere in the data center. You can help ensure the best performance by understanding the impact of the physical storage and the way I/O accesses it.

It is important to know exactly where the virtual media is located on physical storage devices. With Integrity VM, a single physical disk might be sliced into logical volumes or files. Slicing up physical disks increases utilization, but it can affect the performance of the physical device. The guest OS treats the virtual disk as a whole disk, not as a part of a physical one. Over-slicing physical storage can overload a physical device's ability to handle virtual I/O that is meant for whole disks. Figure 7-2 shows a common mistake of overdriving physical storage with multiple guest OS boot disks, which are often I/O intensive.

Figure 7-2 Overdriving Physical Storage Hurts Performance

Overdriving Physical Storage Hurts Performance

Provide workloads that the physical devices can handle for all the virtual devices layered on top of them. Use performance tools on the VM Host, like sar(1M), to see how the physical storage is keeping up with the virtual device demands.

The way the virtual media I/O gets to the physical storage backing it is also an important consideration. As shown in Figure 7-1, all virtual I/O goes through a general VM Host I/O services layer that routes the virtual I/O to the correct VM Host interface driver. The interface driver then controls the physical I/O adapter to issue virtual I/O to the physical storage device. By load balancing across these physical adapters, virtual I/O bottlenecks can be eliminated at the physical hardware layers, thereby increasing performance. Load balancing can be done by installing a multipath solution on the VM Host. See Section : “VM Storage Multipath Solutions” for help with selecting a multipath solution for a virtual media type.

The performance of attached devices is largely determined by the type of physical device attached to the virtual machine. Tapes, media changers, and CD/DVD burners are inherently slow devices, not significantly impacted by the software overhead of Integrity VM.

VM Storage Multipath Solutions

For load balancing and higher availability for virtual machines, consider using a multipath solution on the VM Host. Currently there are no multipath solutions for the attachable device types of tapes, media changers, and CD/DVD burners. However, there are several VM Host multipath options for virtual devices.

Multipath solutions are supported on the VM Host only, not on virtual machines, for the following reasons:

  • The VM Host is the only place where all virtual I/O can be properly load balanced for the best overall performance. A single virtual machine cannot account for all the other virtual machine I/O with which it is competing on the VM Host (see Figure 7-1).

  • Running a multipath solution in a virtual machine does not provide any high availability for a virtual device. Virtual connections between virtual adapters and their devices are never lost until an hpvmmodify command is used to disconnect them. The only connection ever lost is the ability of a virtual device to access its own virtual media through the VM Host. Errors in communication to the virtual media are properly emulated as media errors sent to the guest OS, not path failures.

  • The VM Host does not return specific errors to Integrity VM for hardware path failures. Integrity VM does not detect such events and does not pass them on to the virtual machine.

Each multipath software solution for HP-UX 11.23 interacts at different layers on the I/O stack. Since Integrity VM also interacts with different layers in the I/O stack, only certain options apply to each virtual media type.

Table 7-1 lists the multipath solutions to use on a VM Host for each type of virtual storage media:

Table 7-1 Multipath Solutions

Virtual Media TypeMultipath Options
Whole Disk
EMC PowerPath
HP Autopath/SecurePath
LVM Logical Volume
PVLinks
EMC PowerPath
HP Autopath/SecurePath
VxVM Logical Volume
EMC PowerPath
HP Autopath/SecurePath
VxFS File System
PVLinks
EMC PowerPath
HP Autopath/SecurePath

 

Although Table 7-1 lists the possible solutions for each virtual media type, it cannot determine what is supported on your specific VM Host configuration. Each multipath solution is only supported for specific hardware and software. The solution vendors provide this information for their multipath products. Review the installation and release notes of these products carefully to form a valid VM Host configuration before using it for any virtual machine. Some multipath options do not work together and they all have different load balancing features.

VM Storage Management

Before you decide how to divide VM Host storage, consider the impact on the management of the storage subsystem.

A VM Host administrator manages VM storage to make sure virtual media is allocated safely. This begins with understanding the VM Host I/O stack and knowing where the virtual media is being allocated from.

Figure 7-3 shows an example of a VM Host I/O stack as it applies to a single LUN:

Figure 7-3 Sub-LUN Storage Allocation Example

Sub-LUN Storage Allocation Example

The virtual machine is allocated a logical volume from the LUN for a Virtual LvDisk.

  • The logical volume that has been allocated is marked 1.

  • The parts of the disk that cannot be allocated are marked 2.

Those parts that are no longer available include the files that were on the logical volume and the whole disk that makes up part of the volume group. If any of these parts are allocated for other virtual devices, data corruption can occur on the Virtual LvDisk.

Those parts that are still available for reallocation include other logical volumes that are on the disk,and files that are on those other logical volumes on the disk. These pieces can be allocated without data corruption problems because they do not overlap with the Virtual LvDisk.

Beyond avoiding sub-LUN collisions, whole LUN collisions also need to be avoided. The same storage resource, virtual or attached, cannot be specified more than once to the same virtual machine. Under HP-UX 11.23, most storage device files are defined per path. Be careful not to specify a given device twice. Figure 7-4 shows an example of two device files, /dev/rdsk/c6t2d0 and /dev/rdsk/c11t2d0 pointing to the same physical disk. Once the /dev/rdsk/c6t2d0 device file is specified for a Virtual Disk, the /dev/rdsk/c11t2d0 device file is no longer available.

Figure 7-4 Bad Multipath Virtual Media Allocation

Bad Multipath Virtual Media Allocation

Also, the same storage resource, virtual or attached, cannot be simultaneously shared between virtual machines, unless otherwise specifically exempted. Figure 7-5 shows a Virtual LvDisk being shared across virtual machines, which is not supported.

Figure 7-5 Bad Virtual Device Allocation

Bad Virtual Device Allocation

As these examples illustrate, it is important to know where storage is allocated from to avoid data corruption with virtual machines or even the VM Host. Management utilities such as HP System Administration Manager (sam) and the System Management Homepage (SMH) utilities allow you to track disk devices, volume groups, logical volumes, and file systems. You can use these utilities to annotate devices so that VM Host administrators can see exactly which virtual machines are using each VM Host storage device.

To show each disk only once, management utilities consolidate multipath devices into one disk. When you are dividing up the disk, you should use all the parts of a single disk on a single virtual machine. Allocating different parts of the same disk to different virtual machines makes it difficult to manage and to isolate problems.

VM Storage Changes

Depending on how you set up storage for a virtual machine, the resulting configuration can be more or less difficult to change.

The ability to change virtual media depends on the type of virtual media used. Whole disks are not normally adjustable in terms of size, but some high-end storage enclosures may permit the adjustment of a LUN without losing that LUN's data. Logical volumes are adjustable without losing any data. Finally, files can be changed easily with VM Host file system commands.

No changes to any virtual media can take place on the VM Host until the virtual device that uses the media is removed from the active VM. Attempts to change virtual devices that have I/O active on them is denied by the hpvmmodify command. Once an active virtual machine is allocated virtual media for a virtual device, that virtual machine owns that media and can access it any time. VM Host administrators need to coordinate with VM guest administrators about active virtual machine changes, if the two roles are served by different individuals.

This coordination may also be necessary for attached I/O devices. Once a VM Host device is attached to the virtual machine, it is controlled and owned by that virtual machine. Modifications to the attached device, like changing a tape, can be done physically without detaching the device from the guest. However, such changes may need to be coordinated with the VM Host administrator, especially if the guest administrator has no physical access to the device attached to the virtual machine.

All types of virtual storage devices can be added and removed dynamically from virtual machines. That is, virtual disks, virtual DVDs, tapes, media changers, and CD/DVD burners are all hot-swappable. However, the virtual storage adapters are currently not hot-swappable. Therefore, if all the virtual storage adapters are full, you must reboot the virtual machine when you add additional devices.

Virtual Storage Setup Time

Some virtual devices take longer to set up than others. Whole disks are very easy to set up because they require nothing more than a character device file. This is usually created automatically when the VM Host system is booted.

Logical volume creation is relatively simple. Logical volumes are used widely on HP-UX systems. The sam utility or the Veritas Enterprise Administrator can be used to create logical volumes. With experience, you can use logical volume commands more quickly.

Creating files for virtual devices is not hard, but takes time. Files are usually placed on top of logical volumes, so you might have to create a logical volume first. Use sam to accomplish this.

To create empty files for virtual disks, use the hpvmdevmgmt command (see “Managing the Device Database”).

To create ISO files from physical CD/DVD media for use in virtual DVDs, use the mkisofs(1M) or the dd(1M) utility.

For attached devices, the effort and time to set them up is spent in the creation of the HP-UX pass-through device files that point to the devices being attached. Once understood, making HP-UX pass-through device files is a fast, simple process. If device drivers for the devices are installed on the VM Host, use the hpvmdevmgmt command to quickly create the device files. Otherwise, see scsi_ctl(1M) for information about creating pass-through device files using mknod(1M).

Setting up Virtual Storage

When you add or modify a virtual device, you must enter a resource statement (rsrc). The resource statement can specify either virtual network devices (as described in Chapter 8: “Creating Virtual Networks”), or virtual storage devices.

This section describes how to enter resource statements for use with the hpvmcreate command (described in Chapter 3: “Creating Virtual Machines”) and the hpvmmodify command (described in Chapter 9: “Managing Guests”). The resource statement specifies the virtual storage device that will be seen by the virtual machine and how it maps to the physical storage device on the VM Host.

The outline of a complete resource statement for specifying a virtual storage device is the following:

VM guest storage specification:VM Host storage specification

Where:

For examples of how to construct resource statements, see Section : “VM Storage Resource Statements”.

VM Guest Storage Specification

All virtual storage is addressed from virtual PCI buses. There are 8 PCI buses on the Integrity VM virtual platform. Each PCI bus has 8 slots into which virtual PCI adapters can be placed. One such adapter, simply called scsi, is an emulated single-ported parallel SCSI MPT storage adapter that can be used to connect 15 SCSI target devices to a virtual machine.

A VM Host administrator specifies this SCSI MPT adapter using the following:

device:scsi:pcibus,pcislot,scsitgt

Where:

  • device is one of the following: disk, dvd, tape, changer, or burner

  • pcibus is an integer from 0-6.

    The virtual MPT adapters are only supported on PCI buses 0-6. PCI bus 7 is reserved for other use.

  • pcislot is an integer from 0-7.

    A PCI function number is not specified. It is implicitly zero because the virtual MPT storage adapter supports only a single channel.

  • scsitgt is an integer from 0-14 (15 is reserved for the virtual SCSI adapter).

    Unlike real parallel SCSI bus, there is no arbitration on virtual SCSI buses. The SCSI target IDs for the virtual devices must be unique.The virtual SCSI MPT adapter takes target ID 15 for itself, leaving 0-14 for SCSI targets.

    All SCSI targets connected to a VM are single LUN devices. That is, virtual disks and DVDs are emulated as single LUNs and all attached devices are specified by per LUN VM Host system files. The physical LUN number of an attached device has no impact. All virtual and attached SCSI LUN numbers are implicitly zero and therefore not specified.

    All supported storage device types can share the same virtual SCSI MPT adapter. Up to 15 storage devices can be added to the same SCSI MPT adapter by specifying the same PCI bus and slot numbers.

A virtual SCSI MPT adapter can only be added to a virtual machine if it has a device connected to it.

Not all device types are virtualized. Disk and DVD devices are virtual device types, whose virtual media comes from the VM Host. Tapes, changers, and burners are physical VM Host devices. For these attached devices, the physical SCSI IDs do not determine their place on the virtual bus.

VM Host Storage Specification

Each VM storage device is backed by some VM Host storage entity. A VM Host entity is defined on the VM Host with a system file, which is used by Integrity VM and the VM Host operating system in processing I/O to and from that storage entity.

A VM Host administrator specifies these storage entities using the following specification:

storage:location

Where:

  • storage is one of the following: disk, lv, file, null, or attach

    The selection of storage type defines what VM Host system files apply. For example, lv implies the use of logical volume character device files.

    For virtual devices, the selection of VM Host storage determines what type of virtual media the virtual device will use. For example, the selection of lv for a virtual disk, makes it a Virtual LvDisk to the VM.

    A VM Host storage entity can only be used for one VM device type at a time. For example, a VM Host CD/DVD drive cannot be used for a Virtual DVD and an attached burner at the same time.

  • location is a VM Host system file

    The file permissions on the VM Host system file are not honored by Integrity VM. VM device types that support write operations can still do so using a VM Host system file marked read only.

    There may be more than one VM Host system file that points to the same VM Host storage entity. For example, if there are multiple paths to storage present on the VM Host, there can be more than one disk system file that points to the same disk. Different VM Host system files change how I/O is routed to the VM storage resource, but the system files point to the same storage entity. Therefore, different system files cannot constitute different VM storage resources. A given VM storage resource can only be specified once to a given virtual machine. Therefore, only one VM Host system file per VM Host storage entity can be provided to a virtual machine (see Section : “VM Storage Management”).

Not all virtual device types support all VM Host storage types (see Section : “Integrity VM Storage Implementations”). Complete VM storage resource statements are discussed in the next section.

VM Storage Resource Statements

This subsection provides information on formulating complete valid resource statements for Integrity VM storage devices.

To specify an Integrity VM storage device for a virtual machine, use a complete valid resource statement with the hpvmcreate or hpvmmodify command. The resource statement is a combination of the VM guest resource specification (described in“VM Guest Storage Specification”) and the VM Host Storage Specification (described in “VM Host Storage Specification”). This section provides examples of complete resource statements for each of the following types of virtual storage devices:

A virtual machine can have up to 30 devices total (number of virtual and attached devices).

The maximum size of a virtual storage resource is 2 TB. The minimum size of a virtual storage resource is 512 bytes for virtual disk and 2048 bytes for a virtual DVD.

Do not specify the same storage resource, virtual or attached, for the same virtual machine more than once (see Section : “VM Storage Management”). Unless otherwise noted, storage resources, virtual or attached, cannot be simultaneously shared by virtual machines.

All multipath products for storage resources must run on the VM Host; multipath solutions are not supported in a virtual machine. All multipath solutions used on the VM Host must be in valid supported configurations before being used for Integrity VM storage resources (see Section : “VM Storage Multipath Solutions”).

The resource statements in the following subsections do not contain VM hardware addressing. The PCI bus, PCI slot, and SCSI target numbers are optional.

Virtual Disks

A Virtual Disk is an emulated SCSI disk whose virtual media comes from a VM Host disk LUN. The VM Host disk LUN is specified using a character device file. The character device file is owned by the HP-UX sdisk driver.

Virtual Disk resources cannot be shared simultaneously across active virtual machines (except in certain cluster configurations, as indicated in this manual). Only one active virtual machine at time can be given a particular Virtual Disk resource. Virtual Disk resources can be changed dynamically among active virtual machines.

To prevent virtual media conflicts that can result in data corruption, a proper accounting of how the VM Host whole disks are allocated for use by Virtual Disks needs to be done, as described in Section : “VM Storage Management”.

To provide a multipath solution for a Virtual Disk, see Section : “VM Storage Multipath Solutions”.

If you are using a multipath product, the Virtual Disk resource statement takes the form of:

disk:scsi::disk:/dev/rdsk/cXtYdZ

Where /dev/rdsk/cXtYdZ is an HP-UX character sdisk device file.

These device files can be located for a VM Host LUN using the ioscan command. These system files are installed and removed using the insf and rmsf commands, respectively. Device files are created automatically by the VM Host for any storage it sees during boot. New devices connected or created after boot time, require the use of ioscan and insf to create the new sdisk device files. Old device files for storage not longer present can be removed with rmsf. For example:

# ioscan

# ioscan -funC disk

disk 110 0/5/1/0.11.16.0.0.0.2 sdisk CLAIMED DEVICE HP      A6188A
disk 116 0/5/1/0.11.16.0.0.0.3 sdisk CLAIMED DEVICE HP      A6188A
/dev/dsk/c19t0d3   /dev/rdsk/c19t0d3

# insf -H 0/5/1/0.11.16.0.0.0.2

# ioscan -funC disk

disk 110 0/5/1/0.11.16.0.0.0.2 sdisk CLAIMED DEVICE HP      A6188A
/dev/dsk/c19t0d2   /dev/rdsk/c19t0d2
disk 116 0/5/1/0.11.16.0.0.0.3 sdisk CLAIMED DEVICE HP      A6188A
/dev/dsk/c19t0d3   /dev/rdsk/c19t0d3

In this example, the Virtual Disk Resource Statement is disk:scsi::disk:/dev/rdsk/c19t0d2.

If you are using HP Securepath/Autopath for Virtual Disks, you can use either sdisk device files or virtual device special files (VDSFs). Both device paths provide high availability for the virtual machine and can be used interchangeably. For information about enabling these device paths, see the HP Securepath/Autopath documentation.

If you are using EMC PowerPath for a Virtual Disk, make sure that the sdisk device files that you use for Virtual Disks are enabled for use by the multipath product. Consult the multipath vendor's documentation for more information.

Virtual LvDisks

A Virtual LvDisk is an emulated SCSI disk whose virtual media is provided by a raw VM Host logical volume. To specify a VM Host logical volume, use a character device file. The character device file is owned by either LVM or VxVM.

Virtual LvDisks cannot be shared simultaneously across active virtual machines. Only one active virtual machine at time can be given a particular Virtual LvDisk resource. Virtual LvDisk resources can be changed dynamically between active virtual machines (see Section : “Using Integrity VM Storage”).

Logical volumes can be created using the sam utility or the Veritas Enterprise Administrator. Alternatively, logical volumes can be created using the commands available with the volume manager. All logical volumes are created on whole disks. The sizes of the logical volumes come from the space available from their respective volume group types; that logical volume size can be increased without loss of data in the volume. The character devices for the logical volumes are created by their respective volume managers at the time the logical volume is created. Also to avoid file system corruptions for the VM Host and guest , use only raw logical volumes that contain no VM Host file systems and are not currently mounted on the VM Host.

To prevent data corruptions, keep an account of logical volumes for Virtual LvDisks. To help with the accounting, use all logical volumes within a given volume group for a single virtual machine. When logical volumes are configured this way, you only have to keep track of the volume groups to prevent media conflicts. See Section : “VM Storage Management” for information about tracking virtual media allocation.

If you are using LVM, the Virtual LvDisk resource statement takes the following form:

disk:scsi::lv:/dev/vg_name/rlvol_name

Where /dev/vg_name/rlvol_name is an LVM character device file for rlvol_name on vg_name. To display the LVM character device file name, enter the following command:

# vgdisplay -v
VG Name                     /dev/lvrackA
VG Write Access             read/write
VG Status                   available
Max LV                      255
Cur LV                      4
Open LV                     4
Max PV                      16
Cur PV                      1
Act PV                      1
Max PE per PV               8683
VGDA                        2
PE Size (Mbytes)            4
Total PE                    8681
Alloc PE                    8192
Free PE                     489
Total PVG                   0
Total Spare PVs             0
Total Spare PVs in use      0

   --- Logical volumes ---
   LV Name                     /dev/lvrackA/disk1
   LV Status                   available/syncd
   LV Size (Mbytes)            8192
   Current LE                  2048
   Allocated PE                2048
   Used PV                     1

   LV Name                     /dev/lvrackA/disk2
   LV Status                   available/syncd
   LV Size (Mbytes)            8192
   Current LE                  2048
   Allocated PE                2048
   Used PV                     1

   LV Name                     /dev/lvrackA/disk3
   LV Status                   available/syncd
   LV Size (Mbytes)            8192
   Current LE                  2048
   Allocated PE                2048
   Used PV                     1

   LV Name                     /dev/lvrackA/disk4
   LV Status                   available/syncd
   LV Size (Mbytes)            8192
   Current LE                  2048
   Allocated PE                2048
   Used PV                     1

   --- Physical volumes ---
   PV Name                     /dev/dsk/c4t1d0
   PV Status                   available
   Total PE                    8681
   Free PE                     489
   Autoswitch                  On

In this example, the Virtual LvDisk Resource Statement is disk:scsi::lv:/dev/lvrackA/rdisk2.

To use VxVM, the Virtual LvDisk resource statement takes the form of:

disk:scsi::lv:/dev/vx/rdsk/dg_name/v_name

Where /dev/vx/rdsk/dg_name/v_name is a VxVM character device file for volume v_name on disk group dg_name. To display the VxVM character device file name, enter the following command:

# vxprint
Disk group: rootdg

TY NAME         ASSOC        KSTATE   LENGTH   PLOFFS   STATE    TUTIL0 
PUTIL0
dg rootdg       rootdg       -        -        -        -        -       -

dm disk01       c3t0d0       -        35562538 -        -        -       -

Disk group: VxvmTest1

TY NAME         ASSOC        KSTATE   LENGTH   PLOFFS   STATE    TUTIL0 
PUTIL0
dg VxvmTest1    VxvmTest1    -        -        -        -        -       -

dm disk01       c5t8d0       -        71680564 -        -        -       -

v  vxvm_1       fsgen        ENABLED  2048000  -        ACTIVE   -       -
pl vxvm_1-01    vxvm_1       ENABLED  2048000  -        ACTIVE   -       -
sd disk01-01    vxvm_1-01    ENABLED  2048000  0        -        -       -

v  vxvm_2       fsgen        ENABLED  2048000  -        ACTIVE   -       -
pl vxvm_2-01    vxvm_2       ENABLED  2048000  -        ACTIVE   -       -
sd disk01-02    vxvm_2-01    ENABLED  2048000  0        -        -       -

v  vxvm_3       fsgen        ENABLED  2048000  -        ACTIVE   -       -
pl vxvm_3-01    vxvm_3       ENABLED  2048000  -        ACTIVE   -       -
sd disk01-03    vxvm_3-01    ENABLED  2048000  0        -        -       -

v  vxvm_4       fsgen        ENABLED  2048000  -        ACTIVE   -       -
pl vxvm_4-01    vxvm_4       ENABLED  2048000  -        ACTIVE   -       -
sd disk01-04    vxvm_4-01    ENABLED  2048000  0        -        -       -

To use VxVM, the Virtual LvDisk resource statement is disk:scsi::lv:/dev/vx/rdsk/VxvmTest1/vxvm_2.

For information about multipath solutions for Virtual LvDisks, see Section : “VM Storage Multipath Solutions”.

Virtual FileDisks

A Virtual FileDisk is an emulated SCSI disk whose virtual media comes from a VM Host file. The VM Host file is specified using the absolute pathname to the file. The file can be on a VxFS file system locally mounted on the VM Host. NFS file systems are not supported for Virtual FileDisks.

Virtual FileDisks cannot be shared simultaneously across active virtual machiness. Only one active virtual machine can be given a particular Virtual FileDisk resource at a time. Virtual FileDisk resources can be changed dynamically between active virtual machines (see Section : “Using Integrity VM Storage”).

The file systems used for Virtual FileDisks need to be managed to prevent data corruptions. To help with accounting, it is recommended that all files under a given directory be used with a single virtual machines. Additionally, it may help to allocate file directories from complete logical volumes or whole disks to make the accounting even easier. See Section : “VM Storage Management” for more details.

The Virtual FileDisk resource statement takes the form of:

disk:scsi::file:/pathname/file

Where the /pathname/file specifies the VM Host file used as virtual media.

A VxFS file system can be created on top of a whole disk or logical volume. For files over 2 GB, VxFS requires the file system be marked with a largefiles option. The mkfs command can be used to create the VxFS file systems directly. Once the file systems are created, mount can be used to mount them onto the VM Host file system. Alternatively, if using logical volumes to create the file system on, the volume manager GUIs like sam can be used to create the file systems and their mount points, when the logical volumes are created. In any case, once the file system is mounted, empty files for Virtual FileDisk can be created using hpvmdevmgmt.

# mkfs -F vxfs -o largefiles /dev/dsk/c1t2d0
# mount /dev/dsk/c1t2d0 /fdev/frackA/
# hpvmdevmgmt -S 4G /fdev/frackA/disk1

In this example, the Virtual FileDisk resource statement is disk:scsi::file:/fdev/frackA/disk1.

Multipath options for a Virtual FileDisk device are discussed in Section : “VM Storage Multipath Solutions”.

Virtual DVDs

A Virtual DVD is an emulated SCSI DVD-ROM with virtual media that comes from a disc inside of a CD/DVD drive on the VM Host. The VM Host CD/DVD drive is specified using an HP-UX sdisk character device file.

While the Virtual DVD is read-only, the slowness of the physical VM Host CD/DVD drives prohibits them from being shared across active virtual machines. Thus only one active virtual machine at time should be given a particular Virtual DVD resource. Virtual DVD resources can be changed dynamically between active virtual machines (see Section : “Using Integrity VM Storage”).

The Virtual DVDs, being read-only, do not require management to prevent conflicts writing to the device. However, to prevent potentially sensitive information from being accessed by the wrong virtual machine, make sure you know which virtual machine currently owns the device before you load a CD/DVD. This information can be found on the VM Host with the hpvmstatus commands.

The Virtual DVD resource statement takes the form of:

dvd:scsi::disk:/dev/rdsk/cXtYdZ

Where /dev/rdsk/cXtYdZ is an HP-UX character device file representing a VM Host CD/DVD drive.

Typically, the HP-UX sdisk character file will already be created before booting the VM Host. If it is not, it can be created and managed using the ioscan, insf, and rmsf utilities. For example:

# ioscan -funC disk

disk 0 0/0/2/0.0.0.0 sdisk CLAIMED DEVICE HL-DT-STDVD+RW GCA-4040N
/dev/dsk/c0t0d0   /dev/rdsk/c0t0d0

# diskinfo /dev/rdsk/c0t0d0
SCSI describe of /dev/rdsk/c0t0d0:
             vendor: HL-DT-ST
         product id: DVD+RW GCA-4040N
               type: CD-ROM
               size: 4300800 Kbytes
   bytes per sector: 2048

In this example, the Virtual DVD resource statement is dvd:scsi::disk:/dev/rdsk/c0t0d0.

For a Virtual DVD to be recognized by a virtual machine, physical media must be present inside the VM Host CD/DVD drive. If media is not added at virtual machine start time, it may be inserted into the VM Host CD/DVD drive after the virtual machine is already up. A rescan by the guest OS picks up the new media and adds the Virtual DVD to the virtual machine.

If for some reason the VM Host Administrator requires control of the VM Host CD/DVD drive claimed by a virtual machine but has no media for the VM Host CD/DVD drive, then a Virtual NullDVD should be specified (see Section : “Virtual NullDVDs”). Physical media can then be inserted into the VM Host CD/DVD drive and become virtual media for a Virtual DVD using the hpvmmodify or the virtual console's insert command (see Section : “Guest Administrator”).

After the Virtual DVD is in the virtual machine, the VM Host CD/DVD drive is locked. The VM Host CD/DVD drive is automatically unlocked when the virtual machine is shut down. The VM Host CD/DVD can also be changed while the virtual machine is up using the virtual console's eject command. Once ejected, the Virtual DVD will turn into a Virtual NullDVD and the VM Host CD/DVD drive will unlock. After you place physical media in the VM Host's CD/DVD drive, use the virtual console's insert command to turn a Virtual NullDVD back to a Virtual DVD, relocking the VM Host CD/DVD drive.

Most physical VM Host CD/DVD devices on HP Integrity servers have only one path to them. As such, no multipath software is available on the VM Host for them.

Virtual FileDVDs

A Virtual FileDVD is an emulated SCSI DVD-ROM with virtual media that comes from a VM Host ISO file. The VM Host ISO file is specified using the absolute pathname to the ISO file. The file can be on a VxFS file systems locally mounted on the VM Host. NFS file systems are not supported for Virtual FileDVDs.

The Virtual FileDVD resource statement takes the following form:

dvd:scsi::file:/pathname/file.ISO

Where the /pathname/file.ISO specifies the VM Host ISO file to use as virtual media.

A VM Host ISO file can be created using the mkisofs utility or by using the dd command to copy CD/DVD media to a file. The VxFS file system should be enabled to support largefiles, because ISO files tend to be over 2 GB in size. All the ISO files that are useful to a guest OS should be placed in the same directory to take advantage of dynamic changes using the virtual console (see Section : “Modifying VM Storage Devices”). The ISO files should be marked with proper permissions; they must not be world writable. For example:

# ls -l /var/opt/hpvm/ISO-images/hpux

total 26409104
-rw-r--r-- 1 root sys 3774611456 Jul 11 16:59 0505-FOE.iso
-rw-r--r-- 1 root sys 4285267968 Jul 11 17:05 0512-FOE.iso
-rw-r--r-- 1 root sys 3149987840 Jul 11 18:42 0603-FOE-D1.iso
-rw-r--r-- 1 root sys 1629978624 Jul 11 18:51 0603-FOE-D2.iso

In this example, the Virtual FileDVD Resource Statement is: dvd:scsi::file:/var/opt/hpvm/ISOimages/hpux/0603-FOE-D1.iso.

Virtual FileDVDs, like all files, can take advantage of the multipath options with which the file system is created. See Section : “VM Storage Multipath Solutions” for details.

Virtual FileDVDs are read-only and are sharable across active virtual machines. Use the hpvmdevmgmt command to mark them sharable.

To prevent media conflicts, you must manage Virtual FileDVDs carefully (see Section : “VM Storage Management”). You can see where the file system directory where the ISO file resides using the guest's virtual console. To simplify accounting, allocate file directories from complete logical volumes or whole disks.

Virtual NullDVDs

A Virtual NullDVD is an emulated SCSI DVD-ROM with no virtual media currently present. The next media selection may come from a VM Host CD/DVD drive or VM Host ISO file, depending on how the Virtual NullDVD is configured. Once the next media is selected, the Virtual NullDVD turns into either a Virtual DVD (see Section : “Virtual DVDs”) or a Virtual FileDVD (see Section : “Virtual FileDVDs”) device. As such, a Virtual NullDVD is a transitory state of an empty virtual DVD type.

The choice of how to configure a Virtual NullDVD depends on the access that the VM Host administrator gives to the guest administrator. Virtual DVD changes can be initiated from the virtual console (see Section : “Guest Administrator”). All virtual DVD changes by the guest administrator are constrainted by the actions of the VM Host administrator.

If the VM Host administrator gives access to the guest administrator to load and unload physical media on the VM Host CD/DVD drive, the Virtual NullDVD is set up with the following form of the resource specification:

dvd:scsi::null:/dev/rdsk/cXtYdZ

Where /dev/rdsk/cXtYdZ is an HP-UX character sdisk file that points to the VM Host CD/DVD drive.

This is the same as setting up a Virtual DVD (see Section : “Virtual DVDs”), except that the VM Host CD/DVD might not contain media. The media is expected to come from the guest administrator, who should have access to the VM Host to make such physical media changes. For example:

# ioscan -funC disk

disk 0 0/0/2/0.0.0.0 sdisk CLAIMED DEVICE HL-DT-STDVD+RW GCA-4040N
/dev/dsk/c0t0d0   /dev/rdsk/c0t0d0
# diskinfo /dev/rdsk/c0t0d0

SCSI describe of /dev/rdsk/c0t0d0:
             vendor: HL-DT-ST
         product id: DVD+RW GCA-4040N
               type: CD-ROM
               size: 0 Kbytes
   bytes per sector: 0

In this example, the Virtual NullDVD resource statement is dvd:scsi::null:/dev/rdsk/c0t0d0.

If the VM Host administrator does not want to give access to the VM Host CD/DVD drive to the guest administrator, you can set up a Virtual NullDVD to a file system directory containing the ISO files that the guest administrator wants to access. This resource statement would take the following form:

dvd:scsi::null:/pathname

Where /pathname is the file system directory where the ISO files are located.

This is the same as setting up a Virtual FileDVD (see Section : “Virtual FileDVDs”), except that the file is not specified. By specifying a file directory, the guest administrator can choose which ISO files to use from the virtual console. The file directory must be a locally mounted VxFS file system. NFS file systems are not supported. If the ISO files are world writable, they are not available from the virtual console. For the following ISO files:

# ls -l /var/opt/hpvm/ISO-images/hpux

total 26409104
-rw-r--r-- 1 root sys 3774611456 Jul 11 16:59 0505-FOE.iso
-rw-r--r-- 1 root sys 4285267968 Jul 11 17:05 0512-FOE.iso
-rw-r--r-- 1 root sys 3149987840 Jul 11 18:42 0603-FOE-D1.iso
-rw-r--r-- 1 root sys 1629978624 Jul 11 18:51 0603-FOE-D2.iso

The Virtual NullDVD resource statement is dvd:scsi::file:/var/opt/hpvm/ISO-images/hpux/.

You can configure the Virtual NullDVD to be sharable or have multipath options. If the Virtual NullDVD device is configured to use the VM Host CD/DVD device, it is not sharable and no multipath options are available. If the Virtual NullDVD is configured to use a file system directory, it is sharable and you can use multipath options (see Section : “VM Storage Multipath Solutions”). To mark the directory sharable across virtual machines, use the hpvmdevmgmt command. For example:

# hpvmdevmgmt -m gdev:/var/opt/hpvm/ISO-images/hpux/:attr:SHARE=YES

For more information about using the hpvmdevmgmt command, see Section : “Managing the Device Database”.

Virtual NullDVDs require no additional management beyond that required for the Virtual DVD (see “Virtual DVDs”) or Virtual FileDVD (see Section : “Virtual FileDVDs”) types they become.

Attachable Devices

Integrity VM allows you to attach physical VM Host backup device types to virtual machines. The VM Host backup device types are tapes, media changers, and CD/DVD burners. These devices are specified on the VM Host using HP-UX sctl device files.

The guest OS running on the virtual machine has full control over an attached physical device. Therefore, the guest OS must support the device being attached. See the device's product documentation for a list of supported guest OS drivers.

The resource statements for attached devices take the following forms depending upon device type:

  • For magnetic tape, use:

    tape:scsi::attach:/dev/rscsi/cXtYdZ
  • For media changers, use:

    changer:scsi::attach:/dev/rscsi/cXtYdZ
  • For CD/DVD burners, use:

    burner:scsi::attach:/dev/rscsi/cXtYdZ

Where /dev/rscsi/cXtYdZ is an HP-UX sctl device file to the device type specified.

To create an HP-UX sctl device file, follow these steps:

  1. Run ioscan to pick up any new devices that may have just been connected:

    # ioscan
  2. Locate the device designated for attachment.

    2a. Install any device special files for these new devices:

    # insf -e

    2b. Check to see if the new devices were claimed by VM Host:

    # ioscan -fun

    The following is an example of a claimed tape device:

    tape 1 0/2/1/0.5.0 stape CLAIMED DEVICE HP C7438A
    /dev/rmt/1m            /dev/rmt/c6t5d0BESTn
         /dev/rmt/1mb           /dev/rmt/c6t5d0BESTnb
         /dev/rmt/1mn           /dev/rmt/c6t5d0DDS
         /dev/rmt/1mnb          /dev/rmt/c6t5d0DDSb
         /dev/rmt/c6t5d0BEST    /dev/rmt/c6t5d0DDSn
         /dev/rmt/c6t5d0BESTb   /dev/rmt/c6t5d0DDSnb
    

    If the device is not seen in ioscan -fun, proceed to step 2c. Otherwise, go to step 3.

    2c. If the device is not claimed, make sure the device is at least seen:

    # ioscan -fk

    The following is an example of an unclaimed media changer device:

    Class       I  H/W Path       Driver     S/W State   H/W Type     Description
    ==============================================================================
    
    ext_bus     6  0/2/1/0        c8xx       CLAIMED     INTERFACE    SCSI C1010 
    Ultra160 Wide LVD A6828-60101
    target     35  0/2/1/0.0      tgt        CLAIMED DEVICE 
    unknown    -1  0/2/1/0.0.0               UNCLAIMED   UNKNOWN      HP ThinStor 
    AutoLdr

    If the device is not seen, there is a hardware problem or SCSI ID conflict. Consult the documentation for the particular device to resolve this issue before proceeding.

    If the device is seen but not claimed, this is a result of missing drivers in the VM Host. Integrity VM does not require the drivers to be loaded on the VM Host for the devices to be attached. The HP-UX tape (stape) and changer (schgr) drivers are not loaded by default unless those devices are connected at install time. To load the drivers, use the kcmodule command to statically load the drivers. To complete the installation, the VM Host must be rebooted. Any guests that are running must be shut down before loading these drivers.

    The following is an example of installing the tape driver:

    # kcmodule stape=static

    The following is an example of installing the media changer driver:

    # kcmodule schgr=static

    If you are not loading the VM Host drivers, proceed to step 4.

    If you are loading the VM Host drivers, the devices should show up in ioscan with device files after the VM Host reboot. In which case, proceed to step 3.

  3. Install sctl device files under the /dev/rscsi/ directory using the hpvmdevmgmt command. For example:

    # hpvmdevmgmt -I
  4. Locate a /dev/rscsi sctl device file that corresponds to the device slated for attachment.

    4a. If the device was claimed, the /dev/rscsi file ends with the same cXtYdZ numbers.

    The following is an example of a tape device:

    	Claimed = /dev/rmt/c6t5d0BEST
    	SCTL = /dev/rscsi/c6t5d0
    

    The following is an example of media changer device:

    	Claimed = /dev/rac/c6t0d0
    	SCTL = /dev/rscsi/c6t0d0

    The following is an example of CD/DVD burner device:

    	Claimed = /dev/rdsk/c4t3d2
    	SCTL = /dev/rscsi/c4t3d2

    Once the /dev/rscsi file has been located, proceed to step 5.

    4b. If the device is unclaimed, a /dev/rscsi file must be created containing numbers corresponding to the hardware address.

    The following is an example of locating the hardware address for a tape device:

    ext_bus     6  0/2/1/0        c8xx       CLAIMED
    INTERFACE    SCSI C1010 Ultra160 Wide LVD A6828-60101
    unknown    -1  0/2/1/0.5.0               UNCLAIMED
    UNKNOWN     HP	Ultrium Device Hardware Address = 0/2/1/0.5.0 

    The following shows how the hardware address is broken down into controller, target and device numbers:

    • c is the instance of 0/2/1/0

    • ext_bus is 6

    • t is 5

    • d is 0

    • The sctl file to create is /dev/rscsi/c6t5d0

    To create the sctl device file, see scsi_ctl(1M).

    Use the mknod command, substituting the values in the minor number as noted:

    # /usr/sbin/mknod  /dev/rscsi/devname c 203 0xCCTL02

    Where component parts of the minor number are constructed as follows:

    Minor NumberConstruction
    CCTwo hexadecimal digits, identifying the controlling interface card by its instance number. The instance value is displayed in ioscan output, under column I for the interface hardware type.
    TOne hexadecimal digit identifying the drive (target) address.
    LOne hexadecimal digit identifying the LUN within the device
    0Hexadecimal digit zero, for reserved portion of the minor number.

    The following is an example of the tape device:

    # /usr/sbin/mknod /dev/rscsi/c6t5d0 c 203 0x065002
  5. Use the located or created sctl device file in specifying the attached device.

    For this attached deviceUse this resource statement
    Tapetape:scsi::attach:/dev/rscsi/c6t5d0
    Media changerchanger:scsi::attach:/dev/rscsi/c6t0d0
    CD/DVD burnerburner:scsi::attach:/dev/rscsi/c4t3d0

Attached devices cannot be shared simultaneously across active virtual machines. Only one active virtual machine can be given a particular attached device at a time. However, like virtual devices, attached devices can be attached and detached dynamically across active virtual machines (see Section : “Using Integrity VM Storage”). Also, as the device is being attached to a virtual machine, it cannot be opened by the VM Host at the time of or during attachment.

Because tapes, media changers, and CD/DVD burners are not virtualized, media changes with them must be done physically. Therefore, all media changes with attached devices must be done by individuals with access to that physical storage. Changes to attached devices may require the device to be unlocked from an active guest OS. Attached devices remain in the last lock state the guest OS put it in when the device is detached or the virtual machine is shut down. Empty devices are attached and are not locked.

No multipath solutions are available for attached devices on the VM Host. No multipath products are supported in the virtual machine.

Manage attached devices to prevent the wrong virtual machines from viewing sensitive information. You can display which virtual machines are currently using attached devices using the hpvmstatus command.

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