[mythtv-users] XFS: options when running mkfs.xfs

John Goerzen jgoerzen at complete.org
Thu Sep 6 14:42:28 UTC 2007

On Thu September 6 2007 9:12:58 am Andrew Burgess wrote:
> >I run XFS on my backend, which records both HD and SD stuff.  It is
> > almost always running almost completely full.  I've never defragged
> > since I put it in, and never had the problems you described, either.
> How long has it been running?

And while looking at this, I discovered that I was mistaken about XFS on 
this.  I am surprised, because I use XFS everywhere... but it looks like I 
set this up farther back than I realized, and it was before I started using 
XFS.  So I apologize for unintentionally misleading anyone.  The comments 
about not having playback problems due to fragmentation stand, however.

I will be converting to XFS tonight!

debugfs indicates this filesystem was created in April, 2006.  There has been 
no defragmentation activity since then.  It is possible I grew the 
filesystem since then, though (it is on LVM).  That wouldn't defragment 
anything, but would open up a large contiguous space.

> Would you mind running filefrag *.mpg just for laughs
> and posting a summary?

These files range in size from 647MB to 12GB.  About 2/3 are right around 
2GB.  The remaining 1/3 are 3.7 to 12GB, or 0.6 to 1.5 GB.

They range from 32 to 1513 extents.  About half have between 400 and 500 
extents.  About 1/4 have between 32 and 200 extents.  The remaining 1/4 have 
between 500 and 770 extents, and only two files have more than that.

The number of extents appears to correlate closely with file size.  The file 
with the greatest number of extents is also the largest file on the 
filesystem at 12GB.  That file therefore would average 8MB per extent.  Most 
files appear to average in the 4MB to 8MB per extent range.

> Do you mount with the allocsize= option? What value?

I am mounting these ext3 filesystems with default options save for 
commit=500.  The filesystem features are:

Filesystem features:      has_journal filetype needs_recovery sparse_super

-- John

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