Re: Oracle

Brian Strand (bstrand@switchmanagement.com)
Thu, 06 Dec 2001 15:03:52 -0800


robert.gehr@web2cad.de wrote:

>Hello Brian
>
>Sorry for contacting you directly but I could not find any anser in the
>kernel archive concerning the Problem you described.
>
No problem. I am cc:ing lkml in case anyone else shares this problem,
hopefully you don't mind?

>
>I face a similiar Problem which is as follows:
>
>I wanted to migrate an Oracle Database from a Prliant Server PentiumII
>450Mhz, 450MB, Wide SCSI Raid 5, Kernel 2.2.10,
>Oracle Version 8.1.7 running under Suse 6.2 on an ext2 Filesystem
>
>The new machine is a bit faster concerning the hardware: Proliant Server
>PentiumIII 600Mhz, 512MB , Ultra2 SCSI Raid 5, Oracle 8.1.7 Suse 7.2
>Kernel 2.4.16
>
>I followed the thread and kicked out reiser, replaced it with ext2,
>installed kernel 2.2.20 and tried all those combinations to and fro with
>the flippin result that the new machine is about 2-3 times slower than the
>old one on every combination imaginable. So much for newer kernels,
>filesystems etc.
>
>Have you found a solution to the problem you described in November. If so I
>would be thankful to know
>
Our current best known 2.4.x setup is Suse 7.2 with stock 2.4.16 with
Oracle 8.1.7, running large tablespaces (i.e. temp, rbs, large
data/index tablespaces) on rawio over LVM over RAID10. The performance
seems adequate; unfortunately due to the differing workloads I do not
have exact numbers on 2.2.x vs 2.4.16. I haven't tried 2.2.x on this
server yet due to boot problems. I originally thought it a kernel
issue, but it turns out that the "2.2.x problem" was Oracle bogosity:
Oracle was creating core dump directories 50000+ levels deep upon
startup, running the machine out of VM/file descriptors in the process
(indicated by e.g. "/bin/ls: permission denied" messages even when
logged in as root), from which 2.2.20suse could not recover (2.4.16
handled it adequately). So I guess I should try 2.2.x for comparison
and report the results, although I am rather reluctant to reboot a
production box now that we've got a stable 2.4.x.

What is your workload like? It seems that with RAID5 you might be doing
mostly read-only transactions? Our workload is mostly data warehousing,
with the (large) difference that we do bulk updates (in the millions of
rows) on previously loaded data. I am curious if the slowdowns we have
experienced only affect massively write-bound Oracle instances. Also,
are the number of RAID arrays and the tablespace layout the same across
the two boxes?

Regards,
Brian Strand
CTO Switch Management

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