[mythtv-users] Optimizing performance: xfs fragmentation

[Ian Evans]

On Sat, May 2, 2020, 11:23 PM Stephen Worthington, <stephen_agent at jsw.gen.nz>
wrote:

> On Sat, 2 May 2020 14:38:50 -0400, you wrote:
>
> >A little MythTV math problem.
> >
> >I have a 9 year old 3 TB recording drive with an xfs file system that's
> >never been defragmented and currently has a fragmentation factor of
> 95.88%.
> >
> >If I run xfs_fsr on it for two hours everyday at 5am, how long would you
> >expect it to take to get to a better place? Days, weeks, months?
>
> For MythTV recording drives, fragmentation is not usually a problem.
> MythTV expires recordings when the free space gets too low (somewhere
> below 20 Gibytes), so there is always enough free space for the next
> recording.  That usually means that the fragmentation does not get
> bad.  I use JFS myself, which is also somewhat resistant to
> fragmentation problems.  I do not know enough about XFS to say how
> well it handles fragmentation.
>
> You did not mention how full your recording drive is.  If it has lots
> of free space, then fragmentation is not going to be an issue.  But if
> you are running it as full as MythTV allows, then depending on how
> good XFS is, it could be getting to be a problem, gradually.  But 9
> years is a long time - if you have been running it that full for
> years, and have not noticed any performance issues, then it is
> unlikely to be getting worse and will likely have stabilised at the
> current fragmentation level.
>
> Also, 9 years is a pretty old drive.  I have older, but I am
> progressively replacing my older drives - I really do not want one to
> fail and lose all the data.  A new drive would be much faster and
> could be a lot bigger.
>

The drive has about 200 gigabytes free out of 3 terabytes.

I was actually basing the idea of defragmenting off of the wiki (
https://www.mythtv.org/wiki/Optimizing_Performance#XFS-Specific_Tips) where
one suggestion was to run xfs_fsr for 8 hours overnight via cron. So I'm
that's an outdated recommendation?

>
>
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