Disk Queue Length

[Michael_Smith@xxxxxxxxxxxxxx]

I was looking into performance on my 810.  I was wondering if some of my
Domino applications were having problems with disk contention.
I have a 2757 controller in the 810 with six (6) 4326 (36 GB) drive in
RAID 5 array.  In the 7116 expansion cage, I added five (5) 4327 (70GB)
drives.
I have the six 4326 drives plus the last 4327 in ASP1.  I have the first
five 4327 drives in ASP3.

I copied the member I was interested in from QAPMDISK to another version of
the file in my personal library and started running some SQL statements on
it.

My first question is :  Is the Total Queue Elements column showing all the
I/O request to that drive over the 15 minute interval? The number of
samples taken in the 15 minute interval is 1786 (about 2 a second).  My
typical values for Total Queue Elements range from 50-90 for the 15 minute
interval.  Am I to assume that would translate into slightly more than 2
queue elements every 30 seconds?  (70 TQE/15 min = 4,67/2 samples per
minute = 2.3)

Second question:  Like I said, I have one 70 GB drive in ASP 1 and the rest
are all 36 GB drive.  I notice the 70 GB drive has a higher Total Queue
Element value.  It would make sense that since it's a larger drive, there's
more data on it, so more request for read/write. Does this drive have to
handle request from both ASP's.  The 'standard' read/write from OS/400 and
applications in ASP1 and the checksum at the RAID level for ASP3?

I thought the checksums on the IBM RAID array was contained n the first
four (4) drives of an array.  So, ASP 1 has the OS/400 stuff on the first
four and ASP 3 has the Domino stuff on it's first four.



Michael Smith
Technical Support and Data Center Manager
Farm Family Insurance cos.

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