AIX

Lucky me, someone has installed a server and got it running with the best intentions, but leaving me a headache.

We have a simple p520 with 4 disks. 2x145Gb & 2x300Gb. The smaller disk pair have been built into a VIO mirrored rootvg, and quite right too.

The other two disks form a volume group each (VIO storage pools). The plan was to ensure that disk allocated to the LPARs would be made in pairs, one from each user-volume group so that we would be confident at the LPAR that the hdisk definitions presented would be from different real media. The problem I now have is that we are adding more real disk (another 16x300Gb in a separate CEC) and add more LPARs.

So, should I create more volume groups on the VIO server (storage pools) on a one-disk-one-pool rule, or should I approach this another way. What would be nice would be a way to present the LPAR with a single device made from a mirror at the VIO server and enforcing strictness on the VIO server to make sure that the mirrors are on different real disks.

I feel that if/when we have a disk failure, I'm going to have a huge mess of failed hdisks in the various LPARs we will have and a huge overhead in logging and maintaining disk separation for all these LPAR hdisks and mirrors making sure that LPAR mirrors do not inadvertently end up on the same real disk as the primary copy, albeit a different hdisk that the LPAR sees.

Big question/headache I know. Any suggestions?



Robin
Liverpool/Blackburn
UK

you know if you do it this way, than you loose everything if the vio server goes down ?

Apart from that why dont you just work with vscsi and redundant vio servers rather than with file backed IO - would make maintenance a lot easier I think ...
Regards
zxmaus

That would be wonderful if there was an easy conversion path away from a single VIO server. I have what I have been given.

Should I be looking to unmirror the VIO rootvg, release the disk and then find a way to create another LPAR with dedicated access to the now spare disk? I'm afraid there has been no training and very lttle documentation on VIO.

I have a sinking feeling that you are going to tell me that there should be 2 VIO servers as hardware items segragated from the LPARs somehow. I'[ve tried the IBM website but it's either nothing or Ijust get swamped. I'm obviously not phrasing the search very well.

Given I have one p520 and four internal disks, what am I looking at?

Help!


Apologies if I'm being stupid and missing something obvious.




Robin
Liverpool/Blackburn
UK

One or two VIO is largely a matter of what the Availability requirements of the server are. In general a Production environment should have dual VIO servers. In this config howeer I expect that the issue will be around the use of the Disk Adapters.

Each disk adapter can belong to exactly one LPAR (incl a VIO), so the existing arrangement probably only has one disk adapter - hence one VIO.

If you are buying a new CEC (or is it an I/O drawer? ) you will add at least one more Disk Adapter so you could go to twin VIO. That said its still recommended to mirror the rootvg even in that environment so now 4 disks would be taken up with VIO operating systems.

Even so you'd still be left with the headache of multiple LVs being allocated to each LPAR from each VIO server and the inevitable number of resyncs you'd need after a failure or reboot of a VIO.

The best solution in these kind of environments is to use a Fibre Channel SAN storage array that can then have LUNs connected to each LPAR via one or both VIO servers (depending how you implement it). In that way its the additional pathing that is redundant not the additional disk copy.

If you are going to stick with one VIO and all those new disks - try and get a RAID card so you can create a single RAID array with all the disks, that at least would ease the management of it as the RAID array will take care of keeping the 2 copies of data on separate disks. That said - the I/O performance of this environment will be very poor.

This is criminal, drop me a PM and I may be able to point you in the right direction in the UK to close that skills gap.

cheers
Ross