What is your setting on raid.reconstruct.perf_impact? The default is set to medium. You can try to set it to low and the ls performance might be better. But keep in mind the rebuilds might take longer.
How many disk is in your raidgroup? Keep in mind that when the filer is in rebuild mode, the number of I/O skyrockets. If you have 8 disks in the raidgroup and one disk fails, any single I/O request for a piece of information store in that raidgroup is going to cause 7X the amount of I/O compared to normal operation. This is not peculiar to NetApp but a normal thing for raid.
One other way to get better performance without having the rebuilds take longer is to reduce the number of disk you have in the raidgroup.
Derek
-----Original Message----- From: Jerry [mailto:juanino@yahoo.com] Sent: Friday, October 15, 2004 6:55 AM To: list toasters Subject: parity drive rebuild causing ls hangs
Anyone ever experience really bad performance when rebuilding a parity disk? We had a parity disk fail on our FAS940 and when it was trying to rebuild the disk i/o util went to 100% (observed with sysstat). Reads and Writes did not appear high, but I don't think rebuild traffic effects those numbers.
During this time, "ls" was taking between 30 and 60 seconds (unacceptable). We thought for sure this couldn't be normal, since we've had disks fail and rebuild many times. The difference this time is it was a parity disk, but I don't think that should make a difference other than taking a little longer to rebuild. Sure enough, after the rebuild was complete it started working again. Any opinions?
Jerry
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