ZFS directory with a large number of files

[Ronald Klop]

Not an in depth solution for ZFS, but maybe a solution for you.
mkdir images2
mv images/* images2
rmdir images

Ronald.


On Tue, 02 Aug 2011 09:39:03 +0200, seanrees at gmail.com  
<seanrees at gmail.com> wrote:

> Hi there,
>
> I Googled around and checked the PRs and wasn't successful in finding
> any reports of what I'm seeing. I'm hoping someone here can help me
> debug what's going on.
>
> On my FreeBSD 8.2-S machine (built circa 12th June), I created a
> directory and populated it over the course of 3 weeks with about 2
> million individual files. As you might imagine, a 'ls' of this
> directory took quite some time.
>
> The files were conveniently named with a timestamp in the filename
> (still images from a security camera, once per second) so I've since
> moved them all to timestamped directories (yyyy/MM/dd/hh/mm). What I
> found though was the original directory the images were in is still
> very slow to ls -- and it only has 1 file in it, another directory.
>
> To clarify:
> % ls second
> [lots of time and many many files enumerated]
> % # rename files using rename script
> % ls second
> [wait ages]
> 2011 dead
> % mkdir second2 && mv second/2011 second2
> % ls second2
> [fast!]
> 2011
> % ls second
> [still very slow]
> dead
> % time ls second
> dead/
> gls -F --color  0.00s user 1.56s system 0% cpu 3:09.61 total
>
> (timings are similar for /bin/ls)
>
> This data is stored on a striped ZFS pool (version 15, though the
> kernel reports version 28 is available but zpool upgrade seems to
> disagree), 2T in size. I've run zpool scrub with no effect. ZFS is
> busily driving the disks away; my iostat monitoring has all three
> drives in the zpool running at 40-60% busy for the duration of the ls
> (it was quiet before).
>
> I've attached truss to the ls process. It spends a lot of time here:
> fstatfs(0x5,0x7fffffffe0d0,0x800ad5548,0x7fffffffdfd8,0x0,0x0) = 0 (0x0)
>
> I'm thinking there's some old ZFS metadata that it's looking into, but
> I'm not sure how to best dig into this to understand what's going on
> under the hood.
>
> Can anyone perhaps point me the right direction on this?
>
> Thanks,
>
> Sean
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