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I have a HP P2000 G3 array with two 10Gbit iSCSI controllers in it that presents storage to my virtualisation cluster. It is soon to be expanded with two D2700 shelves each loaded with 25 10k RPM 300GB 6G SAS disks for added performance.

Currently, the two vDisks I have on the first shelf are 'scrubbed' every day, probably more than once, I haven't checked... But either way, it seems like one of the vDisks is being scrubbed at any hour of the day.

How much does disk scrubbing effect array performance? I know that its a disk consistency check and therefore is important, but should I tune this down so they array does not scrub so aggressively?

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  • Why do you scrub virtualised disks? Aug 20, 2015 at 9:15
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    Because the vDisks are just another name for RAID groups and hence are made up from physical disks. The HP array scrubs by default, infact most SAN's do since its how bad disks are detected. Im not referring to virtual hard disks as in virtualisation. Aug 20, 2015 at 9:20
  • it seems like one of the vDisks is being scrubbed at any hour of the day - if the vDisk is large enough and/or has higher load, it might never finish a (default) 24h scrubbing cycle, so they start running back-to-back. I run my disks on a scrubbing schedule of 1 week or even 1 month which I've found to be adequate (never had a second disk fail during replace/rebuild).
    – Zac67
    Feb 11 at 10:42

1 Answer 1

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Scrubbing is a continuous process that monitor state of the hardware and health of the data. it is set to scrub every 24h by default, but you can change this to a value between 1 to 360 Hours, as you can see here

How to enable background scrub?

  1. In the Configuration View panel, right-click the system and 
     select Configuration, Advanced Settings, System Utilities.
  2. Set the options: Either select (enable) or clear (disable) 
     the Vdisk Scrub option. This option is enabled by default. 
     Set the Vdisk Scrub Interval, which is the interval between 
     background vdisk scrub finishing and starting again, 
     from 1–360 hours; the default is 24 hours.
  3. Click Apply.

As it is a background process it scrub the disk in a idle manner if it is not forced to run. It may be desirable to force it to run in case of suspected hardware failure, but the default behavior is to run in background, so my guess is it will not impact much the overall performance of your array. At least it is what I observe on a dozen of MSA I maintain (from P2000, 1040 to 2040 and 2050)

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