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FC-10k tier has disks exceeding low water mark of recommend.
https://3parug.net/viewtopic.php?f=18&t=2934
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Author:  walter_white [ Thu Jul 19, 2018 1:59 pm ]
Post subject:  FC-10k tier has disks exceeding low water mark of recommend.

So InfoSight reported this alert:

"FC-10k tier has disks exceeding low water mark of recommended IOPS"

3Par is a 7200 with 28 10K FC disks.. The low IOPS threshold is 150 while the high is 250.. NinjaStar has it getting 3,000 I/O. All VV are RAID5..

Running statvv throughout the day sees averages around 1,500 IO with a few high spikes and a few low as well..

Is this alert telling me that the SAN is trying to push more IO but the disks are only giving it <100 when they should be giving over 150??

Thanks

Author:  ailean [ Wed Jul 25, 2018 8:34 am ]
Post subject:  Re: FC-10k tier has disks exceeding low water mark of recomm

If it's only some disks it might be a hotspot, maybe one particular LUN with heavy writes keeping the same few disks really busy.

Maybe try looking from the other side, statpd to find the busy disks.

If it is a hot LUN maybe move to a SSD tier if available or QOS it if it's not important.

I've got a few hot disks but the cause was easy to find, couple of LUNs doing 7.5k iops of writes, which of course they mirror.... but can the OS/App teams figure out what it is or why it's doing it..... :(

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