 | | | disk read and processes | disk read and processes 2006-09-21 - By Alexei_Roudnev
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It is not performance issue. You should not expect better write performance
with software based NFS. Use NAS server with embedded cache storage, if you
want better NFS write performance.
35 MB/s on NFS is EXCELLENT speed.
-- -- Original Message -- --
From: <martin@(protected)>
To: "Ronny Egner" <Ronny.Egner@(protected)>; <suse-oracle@(protected)>
Sent: Thursday, September 21, 2006 1:29 AM
Subject: [SPAM] Re: [suse-oracle] disk read and processes
---- Message from Ronny Egner <Ronny.Egner@(protected)> at 2006-09-21
10:16:58 -- ---
>Hi list,
>
>i am struggling with i/o benchmarking and have a few questions:
>
>Our central NAS system has performance issues with
>nfs on solaris. When writing/reading over a gbit-link we see
>"only" 35 mb/s within a single thread. When adding a second
>thread (or process) the throughput increases - up to 80 mb/s with 4
>threads (or processes).
>
>However when writing data to disk with lets say 4 dbw processes
>we can max out the 80 mb/s. But how does reading from disk relates
>to that ? Lets say we do a full table scan in a single session and
>therefore have to read the whole table - does oracle use more than
>one process (or thread) to do that (remember my problem: one session
>or thread can only read 35 mb/s at maximum speed) ?
>
>--
>
>Mit freundlichen Gr??en
>
>Ronny Egner
>Diplom-Ingenieur (BA)
>
Parallel query (PQ) will do exactly that (split a full table scan in more
parts
and then let multiple processes process the parts in parallel).
Caveat: By using PQ you will optimize a single session but with a higher
total
resource consumption (caused by the need for coordination between the
parallel processes).
Martin Berg
Med venlig hilsen
Martin Berg
mobil: +45 30 35 58 68
email: martin@(protected)
web: www.berg-consult.com
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