Re: I/O Performance/bottlenecks on EMC Symmetrix

!! Please do not post Off Topic to this List !!

> The other workload I would say was about the same (Relatively speaking)
> Both machines did have idle time on the CPU (I/O intensive job).

What are the dominant wait events - in Oracle? It sounds like its probably I/O, but you might want to verify - if for no other reason than to have some proof to justify some EMC time and/or a Sym reorg.

> The quicker test machine was a bit stretched on memory at the time (running
> about 8 databases) but not too bad.
>
> The only thing I can think of is pi** poor performance (3 p's you don't
> want in marketing) of the symmetrix disks.
>
> One point this symmetrix is loaded with 36 Gb disks and all of them are
> sliced to pieces and than allocated to filesystems. In theory you can be
> sharing disks with other high I/O apps (E-mail system etc..).

If this is more than just theory, the message from John Hallis most likely hit the nail on the head. I'll lay odds of 3:1 for disk/cache contention in the Sym.

> I do not however have any insight in what is where physically.

My condolences. EMC should be able to help here though, if you don't have another way (ecc, DBtuner, etc.). They should be able to come in, look at the Sym, and tell you what is going on - in cache, against disks, etc. - and also tell you whether it "should be" a problem or not.

There is a common thread to all these good responses you are getting - I/O tuning is still critical, in spite of any vendor propaganda to the contrary.

-Don Granaman
[OraSaurus - Honk if you remember UFI!]

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Don Granaman
  INET: granaman_at_home.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).