Originally posted by: dukessd
I have 6 drives on my p550 which are attached to the on board SAS RAID controller. I want create a raid5 array using the 6 drives and have the raid controller create subarrays (LUNs or hdisks) so I can have different physical disks for my VIOS's rootv's and the LPAR boot disks.
When I boot the diag cd I can create an array and install VIOS but it always creates one big LUN or hdisk and I don't know how I can create multiple ones.
On my xSeries servers the raid controller will let me do that, add all disks to one raid array and then carve out LUNs for ESXServer OS and then data, isn't there such an option for pseries?
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OK, forget the PC stuff, it doesn't apply here - but I'll try to relate stuff to it for your understanding.
With power systems raid whatever array you configure is passed to the operating system as a single disk, after this you can use the OS to carve it up if the OS is VIOS or IVM.
You may want to create one big raid 5 array and you could then use it for a vios and client partitions but this is not recommended - how was the system specified and designed when it was ordered? This may give you the answers you need.
It is not recommended because if you only have one VIOS you should have saved your money and bought IVM instead, and if the single VIOS goes down then so do all the clients, and IBM do not recommend putting client partition disks in the VIOS rootvg.
OK so what are your options and what should / could you do?
The raid adapter means all your storage is on one adapter, so it can only be configured by one partition - the VIOS and only one VIOS partition at that.
So you are stuck with one VIOS - you may as well load up the IVM installation and sell the HMC on Ebay...
Disk configuration options:
One raid5 array - One VG on the VIOS - create logical volumes on the VIOS rootvg for the client rootvgs - IBM do not recommend this. The client lv's would be like the VMware luns.
One mirrored (raid1) array for the VIOS rootvg and then any sort of config for the VIOS to pass the remaining storage to the clients. Here you could create another two mirrored vgs and then use each for two client LPARs rootvgs. Or you could use all four remaining disks in one VIOS 'othervg' and then create logical volumes for each of the client rootvgs and the disks size will be about the only limit to the number of clients you can create. You do not need a raid adapter to do this because AIX and VIOS support software mirroring. Again you need to look at how this system was specified when it was ordered and what the intended configuration was meant to be.
What ever you decide, with only one storage controller you could have got away with the cheaper IVM instead of VIOS / powerVM and you would also have no need for an HMC.
Having spent the money on a VIOS license and an HMC your best bet would probably be to get another storage controller and maybe some more disks and then you can move up to two VIOS partitions for some proper hardware and virtual redundancy.
Whoever specified the system should have has some idea of how it was going to be used, maybe they can let you know what was intended when it was bought.
If you need to brush up on your powerVM then check out
http://www.redbooks.ibm.com/ and search for powerVM, etc.
HTH