victor.engle@gmail.com
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 Posted:
Sat Oct 22, 2005 12:14 am Post subject:
Re: Hitachi 9990 & MPXIO Performance |
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Greg,
Something else occurred to me. Reading your original post I noticed you
said you were doing round-robin load balancing. I think this can cause
problems with the TagmaStor. At least that is what we were told by HP
storage engineering regarding the XP12000 which is a rebranded
TagmaStor. The problem they say is that if a host comes in on CL1-A for
a read, the CHIP processors for CL1-A own the IO and manage the stripe
of data read from disk into cache. Then if the next IO from the host
comes in on CL2-A looking for data blocks in the stripe previously read
through CL1-A there is overhead with the channel processors that may
result in some latency.
We were using VxVM "Balanced Path" which is a bit better than
round-robin and ended up switching to "Preferred Path" and manually
balanced each lun in our 3TB volumes by alternating the preferred path.
Something to consider.
Vic |
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