Serviceguard Extended Distance Cluster (EDC) with VxVM/CVM Mirroring on HP-UX, May 2008

The same vxsnap commands can be used to break off a mirror for off-host processing for example,

to perform a backup, or to refresh data for decision support systems. After the off-host processing is

completed, vxsnap can be used to re-attach the mirror. The VERITAS FlashSnap Point-In-Time Copy

Solutions Administrator’s Guide listed in the “Related Documents

” section provides further examples

and details for off-host processing.

Adding shared storage

When adding shared storage to an EDC, it is important to add the same amount of storage to both

sites. It is also important to adhere to the mirror directives described in the VxVM/CVM features for

an EDC section when adding shared storage to an EDC. For example, the following directives should

be adhered to:

• mirror across enclosures (or across sites with VxVM/CVM 5.0)

• use a version 20 DCO volume for DRL and FMR

Adding LUNs to existing shared disk groups

New LUNs can be added to existing disk groups in an EDC while the disk groups are in use by the

applications running in the cluster. There are a number of steps which must be followed in sequence:

• Make the new LUNs visible to the OS by running ioscan without the “-k” option, in case they

were created after the last reboot or execution of the ioscan(1M) command.

• Make the new LUNs known to DMP and rebuild the device tree in case the LUNs were created after

the last reboot or restart of VxVM (vxconfigd(1M)). This can be achieved by running the

vxdctl enable command.

• If a LUN was never used with VxVM before, run the vxdisk scandisk new command to read

the device tree, which was rebuilt in the previous step.

• A recommended procedure is to initialize a disk to create a “VM” disk, even if the disk was used

with VxVM before. This step can be performed by the vxdisk init or vxdisksetup -i

command, or by one of the wrappers vxdiskadm(1M), or vxdiskadd(1M).

• The final step is to add the VM disk that was just created to the disk group that is used for shared

data in the EDC – this provides new shared storage space. Use the vxdg –g <dg-name>

adddisk <disk-media-name>=<disk-access-name> command for this purpose.

The first three steps must be performed on each cluster node, while the last two need only be

performed on the CVM master node. With the exception of the ioscan(1M) command, all other steps

can be performed with the Veritas Enterprise Administrator (VEA).

Remember to add the same amount of space at both sites so you can use the space in a mirrored

fashion across the two sites.

Extending existing volumes and creating new volumes

If the shared disk groups still have sufficient free space, or new space has been added to the disk

groups as described in the prior step, new volumes can be added or the size of existing volumes can

be increased. This can be accomplished by using VEA or commands like vxresize, vxassist and vxvol.

The vxresize command can be used to change the size of a volume, including the size of a mounted

file system (if the volume contains a file system and if it is a VxFS or CFS), while specifying similar

storage parameters with the vxassist command that was used initially to create the volume. For

example:

“vxresize -g dgEDC vol1 20G mirror=enclr alloc=enclr:DC1-

XP12k1,enclr:DC2-EVA8k1”