By default, HP-UX uses certain naming conventions for physical
volumes, volume groups, and logical volumes. You need to refer to
LVM devices or volume groups by name when using them within SAM,
with HP-UX commands, or when viewing information about them.
Naming Physical Volumes |
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Physical volumes are identified by their device file names,
for example
Note that each disk has a block device
file and a character or raw
device file, the latter identified by the r.
Which name you use depends on what task you are doing with the disk.
In the notation above, the first name represents the block device
file while the second is the raw device file.
Use a physical volume's raw device file
for these two tasks only:
When creating a physical volume. Here,
you use the device file for the disk. For example, this might be
/dev/rdsk/c3t2d0
if the disk were at card instance 3, target address 2, and device
number 0. (The absence of a section number beginning with s
indicates you are referring to the entire disk.)
When restoring your volume group configuration.
For all other tasks, use the block device
file. For example, when you add a physical volume to a volume group,
you use the disk's block device file for the
disk, such as /dev/dsk/c5t3d0.
For more information on device file names, see Chapter 1 of
Configuring HP-UX for Peripherals. See later
in the chapter for examples of using device file names in completing
various tasks and for which commands to use.
All disk device files are created automatically when you boot
the system, after you have physically added the disk. Refer to insf(1M)
for more information.
Naming Volume Groups |
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When choosing a name for a volume group, the name must be
identical to the name of a directory you have created under /dev.
(See Steps 3 and 4 of the example following Table 3-4.) The name
can have up to 255 characters.
Each volume group must have a unique name. For example, typical
volume group names could be vg01,
vgroot, or vg_sales.
Although the name does not have to start with vg,
this is highly encouraged. Often, these names take the form: /dev/vgnn.
When assigned by default, the number nn starts
at 00 and proceeds
01, 02,
and so on, in the order that volume groups are created. By default,
your root volume group will be vg00
although this name is not required; see "Creating the Root Volume
Group and a Root Logical Volume" later for more information on the
root volume group.
Naming Logical Volumes |
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Logical volumes are identified by their device file names
which can either be assigned by you or assigned by default when
you create a logical volume using lvcreate(1M).
When assigned by you, you can choose whatever name you wish
up to 255 characters.
When assigned by default, these names take the form: /dev/vgnn/lvolN
(the block device file form) and /dev/vgnn/rlvolN
(the character device file form). The number N
starts at 1 and
proceeds 2, 3,
and so on, in the order that logical volumes are created within
each volume group.
When LVM creates a logical volume, it creates both block and
character device files. LVM then places the device files for a logical
volume in the appropriate volume group directory.
For example, the default block name for the first logical
volume created in volume group vg01
would have the full path name:
If you create a logical volume to contain raw data for a sales
database, you might want to name it using a non-default name:
After the logical volume in the above example has been created,
it will have two device files:
/dev/vg01/sales_db_lv
(the block device file) |
/dev/vg01/rsales_db_lv
(the character, or raw, device file) |
Naming Physical Volume Groups |
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Physical volume groups are useful for mirroring and are discussed
in Chapter 7. The only naming restriction in this case is that within
a volume group, each physical volume group must have its own unique
name. For example, the volume group /dev/vg02
might have two physical volume groups called /dev/vg02/pvg1
and /dev/vg02/pvg2.
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