Hi all,

System:
XioTech Magnitude SAN
IBM p5 550 with AIX 5.2 and a Cambex PC2000 FC card.
hdisk0 is local
hdisk1 is local
hdisk2 is on the SAN
hdisk3 is on the SAN

My issue is when I copy files either from SAN hdisk to local hdisk, or
one SAN hdisk to the other SAN hdisk I get about 8 MB/s transfer rate
(using iostat and the monitoring of the SAN). A 1.5 MB file takes a
little over 3 minutes. If I transfer that same 1.5 GB file from either
local hdisk to local hdisk OR local hdisk to SAN hdisk, I get 40 - 60
MB/s. The file copies in 30 to 40 seconds.
So basically:
SAN --> SAN slow
SAN --> local slow
local --> SAN fast
local --> local fast

XioTech's docs say to change the queue_depth of the SAN hdisks to 8,
their tech support says to change it to 40, I tried those and kept
trying all the way up to 256 and saw no difference in performance.

So I guess my question is, is this normal performance, or is there an
issue?

Thanks.

In article <1116261706.677478.175400@f14g2000cwb.googlegroups .com>,
"TB" <chessgame@gmail.com> wrote:

> Hi all,
>
> System:
> XioTech Magnitude SAN
> IBM p5 550 with AIX 5.2 and a Cambex PC2000 FC card.
> hdisk0 is local
> hdisk1 is local
> hdisk2 is on the SAN
> hdisk3 is on the SAN
>
> My issue is when I copy files either from SAN hdisk to local hdisk, or
> one SAN hdisk to the other SAN hdisk I get about 8 MB/s transfer rate
> (using iostat and the monitoring of the SAN). A 1.5 MB file takes a
> little over 3 minutes. If I transfer that same 1.5 GB file from either
> local hdisk to local hdisk OR local hdisk to SAN hdisk, I get 40 - 60
> MB/s. The file copies in 30 to 40 seconds.
> So basically:
> SAN --> SAN slow
> SAN --> local slow
> local --> SAN fast
> local --> local fast
>
> XioTech's docs say to change the queue_depth of the SAN hdisks to 8,
> their tech support says to change it to 40, I tried those and kept
> trying all the way up to 256 and saw no difference in performance.
>
> So I guess my question is, is this normal performance, or is there an
> issue?
>
> Thanks.

Do the Fibre connections go straight from the SAN controller to the AIX
box or is there a Fibre router in between? If so, perhaps it's causing
the problem. Can you remove it to see if there's still a transfer
bottleneck?

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Sorry, Should have mentioned that. No, there is no switch. P2P.

Sorry, Should have mentioned that. No, there is no switch. P2P.