Re: poor OCFS performance under Linux

Well, I bet you did not mount the jfs / extfs or whatever filesystem in direct mode. all your i/o got buffered by the OS in main memory. this is faster than going to disk, which the clustered fs would do.

differences will level out when you get heavy load, and do not have memory to spare for unix buffer cache.

Karsten

benwood1_at_airmail.net (Benjamin Wood) wrote in message news:<fae70fe9.0403171408.366bd9fe_at_posting.google.com>...
> I'm having tough time getting good IO performance utilizing OCFS under
> Linux.
>
> I have two x86 servers using QLA2100 cards against a 7 disk fibre
> array configured with software raid-0. The servers are running RHAS
> 3.0 2.4.21-4.EL, Oracle is 9.2.0.4, and OCFS is 1.0.10-1. OCFS was
> created with:
> mkfs.ocfs -F -b 128 -L /var/opt/oracle/oradata/orcl -m
> /var/opt/oracle/oradata/orcl -u `id -u oracle` -g `id -g oracle` -p
> 0775 /dev/md0
>
> I imported a 4 gig table and a count(*) utilizing a full table scan
> against it executed in about 120 seconds. Other operations big IO
> operations, (create datafiles, imports, intensive queries) ran slowly,
> with top indicating about 80% IO wait time.
>
> I configured another database (single node) with identical
> hardware/OS/Oracle/OCFS, utilizing EXT2 and the same query ran in 30
> seconds (same execution plan) and everything was far quicker. For
> kicks, I reformatted the datafile partition to OCFS and things were
> back to running slow on this single node environment. OCFS seems to
> be the weak link here, or at least my implementation of it.
>
> I must be missing something, but scouring the Metalink groups and
> Google didn't come up with anything that's helped...
>
> Many thanks,
> Benjamin
Received on Thu Mar 18 2004 - 06:29:23 CST