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RE: db file parallel write

From: Lim, Binley <Binley.Lim_at_NBNZ.CO.NZ>
Date: Thu, 4 Mar 2004 15:22:41 +1300
Message-ID: <>

Assuming "nothing has changed" is right, problems that suddenly appear, and persist, is likely due to hardware-related issues.

In a previous role, I came a across a similar situation (Solaris server + Netapp) where everything went on a go-slow one fine day. CPU time (sys) shot up to 60-70% whereas normal operation would see it around 20%. Truss shows lots of "poll" syscalls. Filer I/O was also high, but apparently this was not to be interpreted literally, according to the vendor. First question everyone asked was "what has changed"?

After the DBA/sysadmins went around verifying and "proving" that nothing has changed, the vendors replaced a couple of disks, controller boards on the Filer, network cards on both sides, and even changed to different ports on the switch, and the problem went away. Go figure...

> -----Original Message-----
> Sent: Thursday, March 04, 2004 9:34 AM
> To: ''
> Subject: RE: db file parallel write
> Sai
> I recall others on the list mentioning something similar with Netapp.
> Something inherent in the Netapp design. I would google oracle-l netapp
> and
> read the old threads.
> The other possibility is that you may be saturating the network
> connection with a lot of small requests. I would recommend that you tap
> your
> network engineer and have them look at what the wire is experiencing.
> My experience with Netapp has been positive overally but that you must
> be
> careful not to overload the wire.
> Dennis Williams
> Lifetouch, Inc.
> -----Original Message-----
> From:
> []On
> Behalf Of Sai Selvaganesan
> Sent: Wednesday, March 03, 2004 1:37 PM
> To:
> Subject: db file parallel write
> hi
> we are running oracle on red hat and netapp as the storage.
> everything has been going on alright until a week back i/os have become
> very
> slow.
> we can see dbwr taking a very longtime to do a db file parallel write and
> all loadings (this is a dw system) is taking longer. the i/o on the filer
> shows 90% to 95% usage and hits 100% sometimes. this filer is shared
> between
> three other home grown applications but none of them has put in any new
> code. the slowness is showing up on all applications but this dw system is
> bound by some SLAs hence bad performance is easily noticeable.
> we have a tech ticket opened with the vendor but no response yet. has
> anyone
> in this list faced this kind of issues? no sql has changed and this
> storage
> setup has been working fine for more than 6 months now.
> thanks
> sai
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Received on Wed Mar 03 2004 - 20:20:04 CST

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