Preparing the Cluster for Data Replication

When the following procedures are completed, an adoptive node will be able to access the data belonging to a package after it fails over. Use the convenience scripts in the /opt/cmcluster/toolkits/SGSRDF/Samples to automate some of the tasks in the following sections:

mk3symgrps.nodename — to create EMC Symmetrix device groups
mk4gatekpr.nodename — to create gatekeeper devices
mk2imports — to import volume groups
ftpit — to copy the configuration to other nodes in the cluster
pre.cmquery — to split SRDF links before applying the package configuration
post.cmapply — to restore SRDF links after applying the package configuration

These scripts should be copied from /opt/cmcluster/toolkits/SGSRDF to another directory, such as /etc/cmcluster/SRDF.

Installing the Necessary Software

Before any configuration can begin, make sure the following software is installed on all nodes:

Symmetrix EMC Solutions Enabler software allows the management of the Symmetrix disks from the node.
Symmetrix PowerPath software should be installed if you are building an M by N configuration using PowerPath. However, if you are building an M by N configuration using RDF Enginuity Consistency Assist (RDF-ECA), you need to install only Symmetrix EMC Solutions Enabler. You do not have to install any other software.
Metrocluster with Symmetrix SRDF should be installed according to the instructions in the Metrocluster with EMC SRDF Release Notes.




	NOTE: For Metrocluster/SRDF version A.05.01 and earlier, M by N configurations using PowerPath only are supported. As a result, the PowerPath software is a prerequisite for using an M by N configuration with Metrocluster.

Building the Symmetrix CLI Database

The Symmetrix CLI (Command Line Interface) should be installed on all nodes running packages that use data on the EMC Symmetrix disk arrays. Create the EMC Solutions Enabler database on each system using the following steps. (Refer to the Symmetrix EMC Solutions Enabler manual).

Issue the following command on each node after the hardware is installed.

# symcfg discover

This builds the CLI database on the node.

Display what is in the EMC Solutions Enabler database.

symdg list
symld -g symdevgrpname list
symgate list

If the EMC Solutions Enabler database is not configured, the following error message will be displayed:

The Symmetrix configuration could not be loaded for a locally attached Symmetrix




	NOTE: Do not set the `SYMCLI_SID` and `SYMCLI_DG` environment variables before running the symcfg command. These environment variables limit the amount of information gathered when the EMC Solutions Enabler database is created, and therefore will not be a complete database. Also, the `SYMCLI_OFFLINE` variable should not be set since this environment variable disables the command line interface.

Determining Symmetrix Device Names on Each Node

To correctly specify the device file names when creating Symmetrix device groups, be sure to map the HP-UX device files to the R1 and R2 Symmetrix devices. Use the following steps to gather the necessary information:

Obtain a list of data for the Symmetrix devices available, using the following command on each node without any options:
# syminq
Sample output from both the R1 and R2 sides is shown in Figure 5-2 “Sample syminq Output from a Node on the R1 Side” and Figure 5-3 “Sample syminq Output from a Node on the R2 Side”.
Figure 5-2 Sample syminq Output from a Node on the R1 Side
Figure 5-3 Sample syminq Output from a Node on the R2 Side
The following information is needed from these listings for each Symmetrix logical device:
- HP-UX device file name (for example, /dev/rdsk/c3t3d2).
- Device type (R1, R2, BCV, GK, or blank)
- Symmetrix serial number (for example, 50006161), useful in matching the HP-UX device names to the actual devices in the Symmetrix configuration downloaded by EMC support staff. This number is further explained in Figure 5-4 “Parsing the Symmetrix Serial Number”.
  Figure 5-4 Parsing the Symmetrix Serial Number
  The Symmetrix ID is the same as the last two digits of the serial number of the Symmetrix frame, in this example 50.
  The next three hexadecimal digits are the unique Symmetrix device number that is seen in the output of the status command:
  # symrdf -g symdevgrpname query
  This is used by the Metrocluster with Symmetrix SRDF control script and saved in the file /etc/cmcluster/package_name/symrdf.out. The contents of this file may be useful for debugging purposes.
  The next three digits indicate the Symmetrix host adapter (SA or FA) and port numbers; this is useful to see multiple host links to the same Symmetrix device. For example, PV links will show up as two HP-UX device file names with the same device number, but with different host adapter and port numbers.

Use the symrdf command on each Symmetrix disk array (that is, from both the R1 and the R2 side) to pair the logical device names for the R1 and R2 sides of each SRDF link:

# symrdf list

Sample output is shown in Figure 5-5 “Sample symrdf list Output from R1 Side” and Figure 5-6 “Sample symrdf list Output from R2 Side”.




	NOTE: The format of output varies depending on the `symrdf` version.

Sample symrdf list Output from R1 Side

Symmetrix ID: 000187400684
 
                              Local Device View
-------------------------------------------------------------------------
                   STATUS   MODES                      RDF  S T A T E S
Sym        RDF    --------- -----  R1 Inv   R2 Inv ----------------------
Dev  RDev  Typ:G  SA RA LNK  MDA   Tracks   Tracks Dev RDev Pair
---- ----  ------ --------- ----- -------  ------- --- ---- -------------
 
0196 0012   R1:5  RW RW RW   S..        0        0 RW  WD   Synchronized
0197 0013   R1:5  RW RW RW   S..        0        0 RW  WD   Synchronized
0198 0014   R1:5  RW RW RW   S..        0        0 RW  WD   Synchronized
0199 0015   R1:5  RW RW RW   S..        0        0 RW  WD   Synchronized
019A 0016   R1:5  RW RW RW   S..        0        0 RW  WD   Synchronized
019B 0017   R1:5  RW RW RW   S..        0        0 RW  WD   Synchronized
019C 0018   R1:5  RW RW RW   S..        0        0 RW  WD   Synchronized
019C 0019   R1:5  RW RW RW   S..         0          0 RW  WD   Synchronized

Figure 5-5 Sample symrdf list Output from R1 Side

Sample symrdf list Output from R2 Side

 Local Device View
-------------------------------------------------------------------------
                   STATUS   MODES                      RDF  S T A T E S
Sym        RDF    --------- -----  R1 Inv   R2 Inv ----------------------
Dev  RDev  Typ:G  SA RA LNK  MDA   Tracks   Tracks Dev RDev Pair
---- ----  ------ --------- ----- -------  ------- --- ---- -------------
 
0012 0196   R2:13 WD WD RW   S..        0        0 WD  RW   Synchronized
0013 0197   R2:13 WD WD RW   S..        0        0 WD  RW   Synchronized
0014 0198   R2:13 WD WD RW   S..        0        0 WD  RW   Synchronized
0015 0199   R2:13 WD WD RW   S..        0        0 WD  RW   Synchronized
0016 019A   R2:13 WD WD RW   S..        0        0 WD  RW   Synchronized
0017 019B   R2:13 WD WD RW   S..        0        0 WD  RW   Synchronized
0018 019C   R2:13 WD WD RW   S..        0        0 WD  RW   Synchronized
0019 019D   R2:13 WD WD RW   S..         0         0 WD  RW    Synchronized

Figure 5-6 Sample symrdf list Output from R2 Side

Match the logical device numbers in the symrdf listings with the HP-UX device file names in the output from the syminq command. This displays which devices are seen from each node to ensure this node can see all necessary devices.

Use the Symmetrix ID to determine which Symmetrix array is connected to the node. Then use the Symmetrix device number to determine which devices are in the same logical device seen by each node that is connected to the same Symmetrix unit. Record the HP-UX device file names in your table.

Table 5-2 “Mapping for a 4 Node Cluster connected to 2 Symmetrix Arrays” shows a partial mapping for a 4 node cluster connected to two Symmetrix arrays (95 and 50). There may be many R1 and R2 devices and many gatekeepers for each package, so this table will be much larger for most clusters. Also, with M by N configurations, the number of devices increases according to the number of Symmetrix frames.

Table 5-2 Mapping for a 4 Node Cluster connected to 2 Symmetrix Arrays

Symmetrix ID, device #, and type		Node 1 /dev/rdsk device file name	Node 2 /dev/rdsk device file name	Node 3 /dev/rdsk device file name	Nodes 4 /dev/rdsk device file name
ID	95	`c0t4d0`
Dev#	005		`c6t0d0`
Type	R1
ID	50			`c4t0d0`
Dev#	014				`c0t4d0`
Type	R2
ID	95	`c0t2d2`
Dev#	00A		`c0t4d2`
Type	R2
ID	50			`c3t0d2`
Dev#	012				`c4t3d2`
Type	R1
ID	95	`c0t15d0`
Dev#	040		`c0t15d0`
Type	GK
ID	50			`c3t15d1`
Dev#	041				`c5t15d1`
Type	GK
ID	95	`c4t3d2`
Dev#	028		`c4t3d2`
Type	BCV			n/a	n/a




	NOTE: The Symmetrix device number may be the same or different in each of the Symmetrix units for the same logical device. In other words, the device number for the logical device on the R1 side of the SRDF link may be different from the device number for the logical device on the R2 side of the SRDF link. The Symmetrix logical device numbers in these examples were configured to be the same number so the cluster is easier to manage. If reconfiguring an existing cluster, the `Dev` and `RDev` devices will probably not be the same number. When determining the configuration for the Symmetrix devices for a new installation, it is recommended to use the same Symmetrix device number for both the R1 and R2 devices. It is also recommended the same target and LUN number be configured for all nodes that have access to the same Symmetrix logical device.

Preparing the Cluster for Data Replication

Technical documentation

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Installing the Necessary Software

Building the Symmetrix CLI Database

Determining Symmetrix Device Names on Each Node