Standby spare disks in MC/Service Guard environment?

[Mihails Nikitins]

Hi,

Are LVM hot spare disks still not supported in MC/Service guard environment? I have a couple of disks in a shared volume group reported as "available/standby spare". However, no spare disk was taken after hardware fail.

Thanks and points in advance!

[Steven E. Protter]

Shalom,


Hot spare has been supported in LVM for years. If you set up the volume group that gets activated with a hot spare, the hot spare will function normally in a shared, SG activated volume group.

To have a couple of disks has hot spares (or at least one) the way to go is not try and set up a spare volume group but to set up existing volume groups, activated by SG with a hot spare.

I've never seen the need to have more than one hot spare disk in a volume group, so I don't know if more than one hot spare disk is supported. Realistically, with todays disk reliability one hot spare disk per volume group should do the trick.

People may be confused because you don't support it in the serviceguard scripts, you set it up in the Volume group.

http://docs.hp.com/en/B7961-90017/ch03s02.html

There is an excellent section in Charles Keenan's book HP-UX CSE that explains exactly how to set up a hot spare.

Regards and good luck,

SEP

[Mihails Nikitins]

Steven,


Tnaks for your reply. I have a cluster shared group with two physycal volume groups configured. I added two hot spare disks - one per each physical bus. One of disks died, but none of hot spare disks was allocated.

They are displayed as "available/standby spare" What's wrong?

[Sameer_Nirmal · Accepted solution]

Good Question!

Here is my understanding.

LVM Hot Sparing funcationality is only compliant with required MirrorDisk/UX product. That means, the physical volumes has to be mirrored using MirrorDisk/UX to have hot sparing effecive. At the same time this funcationality is only supported on non-clustered node volume groups.

MirrorDisk/UX is not supported in SLVM ( shared VG ), thus hot sparing is out of picture in the environment. In this case, one is supposed to have VG made-up og Hardware RAID which provides its own hot sparing.

http://docs.hp.com/en/B2355-90950/B2355-90950.pdf ( page 641 )

There is LVM Online Replacement ( LVM OLR )featured offered which is supportted with SG as well. This feature requires applying a LVM patch for respective version of HPUX OS.

[Mihails Nikitins]

Thank you. I checked that generally hot-sparing works for MC/SG, multiple spares are supported. I had a specific problem that is out of scope of this thread.