On 09/16/2014 08:39 AM, Alan Robertson wrote:
On 09/16/2014 09:12 AM, Ski Kacoroski wrote:
Hi,
We installed a new student records system over over the summer that
runs on MS SQL server. Everything seems to be ok, but for one thing
that I am not sure is an issue waiting to bit me or something I can
ignore. On the SAN, the volume for the transaction logs has 125ms
read response times (write response times are around 2ms). This is
the only volume on the SAN with such large response times. Has anyone
seen this before and if so, is it something I need to be concerned about.
Since write times are fast, then it's not likely a SAN congestion
issue. Is the transaction log RAID5? Are there rebuilds in progress?
125ms is really really slow. It's about 10x slower than the real
underlying disk - including seek times. Unless you have a rebuild
underway, it sounds broken to me.
If you can afford it (and you probably can), I'd recommend RAID10 for
transaction logs - or even RAID1 SSD (even though it's pricey,
transaction logs aren't usually huge).
The disks are RAID1+0, 10k. And yes I agree something is fishy here as
this the only place I see the problem on the SAN.
We are no where near the maximum IOPs on the array so that is not the
problem.
I am not sure about SAN disk alignment - I will check on this with the
vendor.
Thanks for all the replies.
cheers,
ski
--
"When we try to pick out anything by itself, we find it
connected to the entire universe" John Muir
Chris "Ski" Kacoroski, [email protected], 206-501-9803
or ski98033 on most IM services
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