Disk controller vs another disk

Hi,
Since I added a couple databases and a lot of users to my SQL server, I
notice that my disk queue lenght is now too high and I need to add disk(s) t
o
increase performance. My server is configured in a clustered environment and
the data is on a SAN. The SAN use RAID1 for my partition and the controller
of the disk has a 128mb cache. I have 125 databases on this server for a
total of 80GO of data.
I had a discussion with someone in the ''hardware team'' and he said that
if we change the controller card for a card that will have 1GB of cache, it
will be better than add another disk in term of performance. I searched on
the web and in some newsgroups and I found nothing that suggest this kind of
thing. What is your opinion ?"TheOne" <TheOne@.discussions.microsoft.com> wrote in message
news:692914A2-F957-4E00-809E-DDB3BFFC878B@.microsoft.com...
> Hi,
> Since I added a couple databases and a lot of users to my SQL server, I
> notice that my disk queue lenght is now too high and I need to add disk(s)
> to
> increase performance. My server is configured in a clustered environment
> and
> the data is on a SAN. The SAN use RAID1 for my partition and the
> controller
> of the disk has a 128mb cache. I have 125 databases on this server for a
> total of 80GO of data.
> I had a discussion with someone in the ''hardware team'' and he said that
> if we change the controller card for a card that will have 1GB of cache,
> it
> will be better than add another disk in term of performance. I searched on
> the web and in some newsgroups and I found nothing that suggest this kind
> of
> thing. What is your opinion ?
Impossible to tell without testing. He's right that the remedy for for IO
contention and disk queuing is as likely to be adding memory as adding
disks. The reason is that better caching will reduce the number of IO's
needed by the workload. But adding cache between the server and disk by
adding it on the controller is generally vastly more expensive than simply
adding more memory to the server.
David|||TheOne,
Additional cache is good, but as always ... "your results may vary". It is
very difficult to estimate cacheing performance. Why not do both? Add a new
controller and see if it makes a difference. If not, add a disk drives to
the SAN.
-- Bill
"TheOne" <TheOne@.discussions.microsoft.com> wrote in message
news:692914A2-F957-4E00-809E-DDB3BFFC878B@.microsoft.com...
> Hi,
> Since I added a couple databases and a lot of users to my SQL server, I
> notice that my disk queue lenght is now too high and I need to add disk(s)
> to
> increase performance. My server is configured in a clustered environment
> and
> the data is on a SAN. The SAN use RAID1 for my partition and the
> controller
> of the disk has a 128mb cache. I have 125 databases on this server for a
> total of 80GO of data.
> I had a discussion with someone in the ''hardware team'' and he said that
> if we change the controller card for a card that will have 1GB of cache,
> it
> will be better than add another disk in term of performance. I searched on
> the web and in some newsgroups and I found nothing that suggest this kind
> of
> thing. What is your opinion ?