I just tried it again. I create two raid1 devices and build a raid0 with
them. This way it is syncing both raid1 siumltaneous with ~4000k/s which
is then ~23min in my situation. If I build two raid0 and then raid1 on
them, I get just one sync with the minimum 100k/s and estimated 2240
minutes. So this seems to be the wrong way.
-Simon
Simon Matter schrieb:
>
> Thomas Duffy schrieb:
> >
> > I have setup a little (280G) xfs on RAID 10 (RAID 1 on RAID 0). This
>
> Some time ago I was playing with similar setup. IIRC I saw the same slow
> resync speed. I then turned my RAID upside down and everything was okay.
> I dont know how but since you said 'RAID 10 (RAID 1 on RAID 0)' I guess
> you could just make it (RAID 0 on RAID 1) and it should be okay. In may
> case sync speed was then ~10000-40000 w/o tuning. I'm interested to hear
> what came out after.
>
> > has 8 SCSI drives (4 per card).
> >
> > Everything seems to work fine, expect the RAID resync craaaawwwllllsss.
> > It goes at the minimum of 100k/s which should take a few months to
> > finish syncing :) It sometimes bumps up to 250 k/s, but never higher
> > even with no system activity.
> >
> > First off, does anyone know of a way to bump the sync rate up? Could
>
> I put this in my /etc/sysctl.conf
> # Force RAID reconstruction to run with high priority
> dev.raid.speed_limit_min = 5000
>
> Usually you should not need this. If it does not sync fast while there
> is no load on the box, something else is not good. But if you have
> constant load on the box you really need the higher value than the
> default (100).
>
> > this be some sorta weirdness between XFS and MD that is causing the slow
> > resync? On a simple RAID 1 setup (2 disks) w/ XFS on the device, the
> > resync is as speedy as the SCSI card allows when there is no other I/O
> > which is what I would expect from MD.
> >
> > Other info, I am using 64k chunk sizes on both the RAID 1 and RAID 0
> > with 4k block sizes on XFS (obiviously because it on i386). These are
> > 10000 rpm ultra SCSI 3 drives, so they should scream. I was able to dd
> > a blank 200G file relatively fast using bs=64k on this device, so it
> > seems to be ok with creating/copying files.
> >
> > Thanks for any help,
> >
> > -tduffy
>
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