[mythtv-users] XFS RAID Tweaking

Rob Dege livemotion at gmail.com
Fri Oct 22 12:56:16 UTC 2010

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).

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 :)


On Thu, Oct 21, 2010 at 5:51 PM, Keith Edmunds <kae at midnighthax.com> wrote:

> On Thu, 21 Oct 2010 14:13:11 -0400, 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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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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