Disk Queue Length counters not meaningful in SQL 2000?

bertcord_at_gmail.com
Date: 01/27/05 

Date: 27 Jan 2005 13:34:43 -0800

Yeah that's what I said...what are they talking about. I am in the
process of doing some research on multiple files vs. multiple
filgroups. I have seen it discussed a bunch on these groups but I need
to perform some tests to back it up. During my research I came across
the following from the "SQL Server 2000 Operations Guide"

"Note on Disk Queue Length

This counter no longer yields meaningful results in interpreting disk
I/O problems with SQL Server 2000. This is because the SQL Server
engines dynamically manage disk I/O, which is why the Max Async I/O
setting no longer exists. A simplified explanation is that SQL Server
issues an order for disk I/O, but does not wait for that process to
complete before issuing another request. When the I/O request has
completed its work, the database engine is notified and processes the
results. SQL Server monitors the throughput on these requests, and will
manage the amount of I/O that the disks can effectively handle."

You can see it here
http://www.microsoft.com/technet/prodtechnol/sql/2000/maintain/sqlops6.mspx

can anyone make any sense of this.
"SQL Server monitors the throughput on these requests, and will manage
the amount of I/O that the disks can effectively handle."

ok what does this mean? it will mange the amount of IO...ok how.
Has anyone seen this, or has an explanation?

Thanks
Bert

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