[mythtv-users] XFS RAID Tweaking
belcampo
belcampo at zonnet.nl
Fri Oct 22 13:08:30 UTC 2010
Rob Dege wrote:
> Hi Keith,
>
> I'm not having any problems with my RAID atm. In fact things are
> working fine :)
>
> I was forced to upgrade the mysql server on my mythbox, and was
> searching for ways to optimize it, when I stumbled upon that wiki page.
> Reading the entire page, I discovered that my XFS /myth partition was
> 98% fragmented, which forced me to upgrade xfsprogs so that I could
> defrag the drive (the version that was installed didn't have the defrag
> utility).
To almost prevent fragmentation, you can add allocsize=512M or 1024M to
your xfs mount options in fstab.
At least xfs_fsr will be much faster because of much less fragmentation.
>
> After seeing this success, I wanted to try and tweak XFS on RAID.
> However, I don't know if I can tweak the mount options if the sunit and
> swidth were specified when I originally formatted the partition. Hence
> my question (btw, do you know if that's advisable or not?)
>
> Thank you for your concern about my RAID setup, but I'm okay with the
> risks. The partition only holds the recorded TV shows, and I'm okay if
> they get lost in a RAID crash. I chose a RAID0 over a RAID1 setup b/c
> of the improved performance. I have 5 tuners on my box (3 SD, 2 HD),
> and I needed the extra write performance to handle all 5 tuners
> recording at once while I simultaneously watch a show.
>
> Thank you for the mentioning the tip about mdadm's email alerts. I'll
> have to look into that. I like the idea of that feature. I just hope
> it was available when FC3 was released :)
>
> -Rob
>
>
> On Thu, Oct 21, 2010 at 5:51 PM, Keith Edmunds <kae at midnighthax.com
> <mailto:kae at midnighthax.com>> wrote:
>
> On Thu, 21 Oct 2010 14:13:11 -0400, livemotion at gmail.com
> <mailto:livemotion at gmail.com> said:
>
> > is it okay to
> > add the custom sunit and swidth values to the mount options, even
> though
> > they wouldn't match the values on the partition?
>
> What problem do you have that you are trying to solve?
>
> An observation: with RAID0, you will lose all the data on the RAID
> device
> if any of the underlying physical devices fail. You're already three
> years
> nearer the time when the first of those disks to fail will actually
> do so.
> You don't say what size your RAID0 partition is, but you may want to
> consider buying two disks that are each (at least) the size of your
> RAID0
> partition, and implementing them as RAID1, therefore giving you some
> fault
> tolerance. If you do that, set up mdadm to email you if the array
> becomes
> degraded.
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>
>
>
> --
> -Rob
>
> Hell hath no fury like a snowplow driver from Cheektowaga who gave
> up cable and Canadian beer so he could afford Bills season tickets.
>
>
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>
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