Re: disk subsystem performance question

Battery backup on the controller should help in this case. If there is none, "write back" mode should be used (instead of "write through"), loosing advantages of on-board caching (still helps with the "reads").

Igor Neyman, OCP DBA
ineyman_at_perceptron.com

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, April 10, 2002 6:58 PM

> Much of the supposed 'speed' may come from onboard
> caching on the controller. There is the minor risk
> that a crash could come after Oracle commits the data
> and before it is actually written to disk.
>
> --- John.Dailey_at_ing-fsi-na.com wrote:
> > Hi all,
> >
> > We are running both a Hitachi 7700E and a 9960 disk
> > subsystem here and we
> > are getting ready to move our production DBs from
> > the old(7700E) to the
> > new(9960) Hitachi. We have had trouble in the
> > past on the 7700E due to
> > disk contention and layout, i.e. we weren't striped
> > across the array groups
> > very well.... this caused pretty poor I/O
> > performance. This has been
> > a learning experience for the DBAs and the SAs here
> > for the logical vs.
> > physical aspects of our disks. Anyway, to make
> > a long story short, we
> > are ordering disk for the move to the 9960 and we
> > have 2 choices in disk
> > sizes - 18GB and 73GB, and 2 choices in RAID - 1+0
> > and 5. I would like
> > to get the smaller, faster 18GB drives in a RAID 1+0
> > configuration and
> > stripe our data across the array groups as wide as
> > possible. However, I
> > am running into objections from the Hitachi people
> > that their system is
> > "soooo fast we need not worry about such minor
> > details". I'm having a
> > hard time believing that given our I/O problems on
> > the 7700E. Performance
> > is given a high priority here.
> >
> > What I would like to know is others' experience with
> > disk subsystems -
> > specifically Hitachi but EMC and others as well....
> > have you been able to
> > "throw the disk in and forget it" or have you had
> > success in getting to the
> > dirty details? Have you tested or noticed an
> > improvement with smaller,
> > faster drives in a disk subsystem like the Hitachi
> > or have you traveled
> > that path and found no noticeable improvement?
> > I'm looking for either
> > a) ammunition that my view is correct, or b) I'm
> > wrong and we can get
> > bigger drives which will make Enterprise Planning
> > very happy from a $$$
> > standpoint because our Hitachi capacity will last
> > longer.
> >
> > We are running Oracle 8.1.7 / AIX 4.3.3 / Peoplesoft
> > Financials version 8.
> > 2 production databases , one 400 GB and the other
> > about 1TB. We've got
> > some other production DBs but these are our big
> > guys.
> >
> > Thanks in advance for any and all input - any help
> > is greatly appreciated.
> > I'd be happy to share any info we have found up to
> > this point and our
> > experiences on the 7700E as well if anyone is
> > interested - despite the fact
> > I will probably bore you to death :-)
> >
> > John Dailey
> > Oracle DBA
> > ING Americas - Application Services
> > Atlanta, GA
> >
> >
> >
> > --
> > Please see the official ORACLE-L FAQ:
> > http://www.orafaq.com
> > --
> > Author:
> > INET: John.Dailey_at_ing-fsi-na.com
> >
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> =====
> Pete Barnett
> Lead Database Administrator
> The Regence Group
> pnbarne_at_regence.com
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Igor Neyman
  INET: ineyman_at_perceptron.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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