XFS: Abysmal write performance because of excessive seeking (allocation groups to blame?)

Peter Grandi pg_xf2 at xf2.for.sabi.co.UK
Thu Apr 5 17:41:01 CDT 2012

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> Apparently not many people have figured out in the Linux
> culture that general purpose filesystems cannot handle well
> large groups of small files, and since the beginning of
> computing various forms of "aggregate" files have been used
> for that, like 'ar' ('.a') files from UNIX, which should have
> been used far more commonly than has happened, and never mind
> things like BDB/GDBM databases.

As to this, another filesystem strongly oriented at massive
streaming, Lustre, is sometimes used for small-file workloads,
and one of the suggestions given for that is to put the small
files inside an 'ext2' filesystem in a file, and mount it via
'loop'.  That is to use 'ext2' (or some other filesystem type)
as an archive format. That is less crazy than it seems.

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