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XP24K and sequential IO issue

Jean-Baptiste Broccard
Occasional Advisor

XP24K and sequential IO issue

Hi All,

I use XP24K for my oracle DB w/ HPuxV3.

We configured storage like this:
fc1 and fc2 -> all LUNs for Data
fc3 and fc4 -> 2 LUSE for Redo , let's call them: LUSE-1, LUSE-2

Redologs are not stripped accross these 2 LUSE: 1 Redolog is dedicated per LUSE.

We followed the best practice guide by telling the system do not load balance IO for these 2 LUSE (in order to let XP detect sequential IO and leverage it).

Unfortunately, the Load balancing was configured with preferred path, and IO are almost all going through 1 Path (not all).

XP detect like 90% Random IO on these LUSE.

Does it come from the loadbalancing even if we have preferred path set ?

What should we do ?
Another documentation say we can disable 1 lunpath. The guys who take care of storage say that if I disable 1 lunpath, i will disable the entire FC connexion ! But I don't think so, since, when invoking disable lupath, you have to provde the HWpath including the WWID of the LUN. Did I miss something ?

Another solution would be to disable legacy mpath, they say that needs a reboot and it's risky. The same doc, they show that they do that on the fly. What do you think ?

I wish my redo would kick more a$# !