PERC RAID Controller settings?

[abefuzzleduser2]

We have a Dell 6450 quad 1.6MHz, 4GB RAM running SQL 2000 on Win 2000
server with 2 PERC3/QC cards. Server has 4 internal drives configured
as two raid-1 drives (OS and SQL logs). Server has 7 more drives in
external drive rack for RAID-5 SQL data. We did not have a UPS
available for server at installation so I set cache as write-through,
even though should not matter since it writes back at restart right?.
I am planning on switching back to write-back cache and was wondering
how do users run this setting and any problms/caveats? How do I tell
if the PERC cards are mirrored? Or does one PERC card run 4 internal
drives and other card run raid5? How much performance boost do you
get from using write-back? What are the recommended settings for read
cache (readahead, adaptive etc)? Can you post some reference web
sites? Thanks P

[John Bell]

Hi

The Dell OpenManage application should tell you how the cards are
configured. I would not expect or think that the cards are mirrored. I would
suspect that the external array is driven by one card and I would
expect/hope that each raid 1 set is on a separate channel of the other card.
On a file server enabling write back cache is advisable when the cards
themselves provide a battery backup rather than the presence of a UPS. SQL
Server usually assumes that there is no write caching and for that reason
some people say don't have write back caching. I have also seen database
corruption and errors with write caching on IBM servers and SQL Server 7.

You may want to look at this article and others on:
http://www.sql-server-performance.co...nce_audit3.asp
John

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We have a Dell 6450 quad 1.6MHz, 4GB RAM running SQL 2000 on Win 2000
server with 2 PERC3/QC cards. Server has 4 internal drives configured
as two raid-1 drives (OS and SQL logs). Server has 7 more drives in
external drive rack for RAID-5 SQL data. We did not have a UPS
available for server at installation so I set cache as write-through,
even though should not matter since it writes back at restart right?.
I am planning on switching back to write-back cache and was wondering
how do users run this setting and any problms/caveats? How do I tell
if the PERC cards are mirrored? Or does one PERC card run 4 internal
drives and other card run raid5? How much performance boost do you
get from using write-back? What are the recommended settings for read
cache (readahead, adaptive etc)? Can you post some reference web
sites? Thanks P