Hello Anantha, Wednesday, January 17, 2007, 2:35:01 PM, you wrote:
ANS> You're probably hitting the same wall/bug that I came across; ANS> ZFS in all versions up to and including Sol10U3 generates ANS> excessive I/O when it encounters 'fssync' or if any of the files ANS> were opened with 'O_DSYNC' option. ANS> I do believe Oracle (or any DB for that matter) opens the file ANS> with O_DSYNC option. During normal times it does result in ANS> excessive I/O but is probably well under your system capacity (it ANS> was in our case.) But when you are doing backups or clones ANS> (Oracle clones by using RMAN or copying of db files?) you are ANS> going to flood the I/O sub-system and that's when the whole ZFS ANS> excessive I/O starts to put a hurt on the DB performance. ANS> Here are a few suggestions that can give you interim relief: ANS> - Seggregate your I/O at filesystem level; the bug is at the ANS> filesystem level not ZFS pool level. By this I mean ensure the ANS> online redo logs are in a ZFS FS that nobody else uses, same for ANS> control files. As long as the writes to control and online redo ANS> logs are met your system will be happy. ANS> - Ensure that your clone and RMAN (if you're going to disk) ANS> write to a seperate ZFS FS that contains no production files. ANS> - If the above two items don't give you relieve then relocate ANS> the online redo log and control files to a UFS filesystem. No ANS> need to downgrade the entire ZFS to something else. ANS> - Consider Oracle ASM (DB version permitting,) works very well. Why deal with VxFS. ANS> Feel free to drop me a line, I've over 17 years of Oracle DB ANS> experience and love to troubleshoot problems like this. I've ANS> another vested interest; we're considering ZFS for widespread use ANS> in our environment and any experience is good for us. ANS> Also as an workaround you could disable zil if it's acceptable to you (in case of system panic or hard reset you can endup with unrecoverable database). -- Best regards, Robert mailto:[EMAIL PROTECTED] http://milek.blogspot.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
