Hi Anantha, I was curious why segregating at the FS level would provide adequate I/O isolation? Since all FS are on the same pool, I assumed flogging a FS would flog the pool and negatively affect all the other FS on that pool?
Best Regards, Jason On 1/17/07, Anantha N. Srirama <[EMAIL PROTECTED]> wrote:
You're probably hitting the same wall/bug that I came across; ZFS in all versions up to and including Sol10U3 generates excessive I/O when it encounters 'fssync' or if any of the files were opened with 'O_DSYNC' option. I do believe Oracle (or any DB for that matter) opens the file with O_DSYNC option. During normal times it does result in excessive I/O but is probably well under your system capacity (it was in our case.) But when you are doing backups or clones (Oracle clones by using RMAN or copying of db files?) you are going to flood the I/O sub-system and that's when the whole ZFS excessive I/O starts to put a hurt on the DB performance. Here are a few suggestions that can give you interim relief: - Seggregate your I/O at filesystem level; the bug is at the filesystem level not ZFS pool level. By this I mean ensure the online redo logs are in a ZFS FS that nobody else uses, same for control files. As long as the writes to control and online redo logs are met your system will be happy. - Ensure that your clone and RMAN (if you're going to disk) write to a seperate ZFS FS that contains no production files. - If the above two items don't give you relieve then relocate the online redo log and control files to a UFS filesystem. No need to downgrade the entire ZFS to something else. - Consider Oracle ASM (DB version permitting,) works very well. Why deal with VxFS. Feel free to drop me a line, I've over 17 years of Oracle DB experience and love to troubleshoot problems like this. I've another vested interest; we're considering ZFS for widespread use in our environment and any experience is good for us. This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
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