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XP disk system LUN/LDEV layout for AIX host.

Simon 1982
Occasional Contributor

XP disk system LUN/LDEV layout for AIX host.

I am currently planning an upgrade of a AIX host connected to a HP XP12000 disk system.. The workload is a Oracle DB server for Oracle applications. I have read quite a few documents concerning the "ideal layout layouts of the XP 12000" and I would like to ask a few questions.

1.) How far from ideal is our current config?

Current Config:
2 x 2Gbps front end ports.
25 x LUSE assigned to host. (15.1GB LDEV*2 2D+2D RAID, 73GB disks). Within each of the LUSE's, the LDEVs comes from a different RAID Group) A total of 6 different Raid Groups within the same CU are used.
VGs consist of 1 or 2 LUSE's. However, the LUSE's come form the same Raid Group. No LV level striping.
No multipathing. (AIX 4.3.3 Limitation)

===========================

Given the following resources on our XP12000
- 4 x 2 Gbps Front end ports from a 8 port CHIP pair.
- 4 x 2D +2D RAID 1 Raid Groups made from 72GB drives.
- 15.1GB LDEVs have been created from the RAID groups. The LDEV's will come from 4 different RG within the same CU.
- Host has 2 Dual port 4Gbps HBA's.

2.) Will the following configuration be better than our existing layout? Is there anything else we could do?
- VG's will be created from 4 LDEV's from different RAID groups.
- LV's will be striped across the 4 LDEVs PV's with 2 or 4 MB stripe size.
- Each of the VG's 4 LDEV's be presented via a different path.
- Host level MPIO will be used and a alternative path from Host to LDEV will be created. Round Robin will not be used.

Other questions
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3.) Will there be any benefit of increasing VGs to 8 LDEV's from difference Raid groups and a LV across all 8 of them?
4.) Is there anyway for us to check which RAID group connects to which ACP MP?
5.) If we want to spread the load even more, would it be advisable to create VG from 16 LDEV's from different RAID groups and create LV stripes across all 16 of them even if the RAID Groups come from the same set of 8 ACP backend fibre loops?

Thanks in advance.

Simon