Re: HAMMER update 10-Feb-2008

["Adrian Chadd" <adrian@xxxxxxxxxxx>]

Well, unless someone implements some kernel-space globbing support
(which would be nice for other reasons, alas..) then you may still be
stuck with similar issues.

of course, ls *match* | xargs -n 100 rm or something along those lines
is a perfectly good way of doing it..


Adrian


On 11/02/2008, Bill Hacker <wbh@conducive.org> wrote:
> Matthew Dillon wrote:
> >     HAMMER is really shaping up now. Here's what works now:
>
> *snip*
>
> >     I have already run some tests with regards to the blockmap allocation
> >     model and it looks very good.   What I did was implement an array of
> >     blockmap entry structures rather then just an array of pointers to the
> >     actual physical big-blocks.  The blockmap entry structure not only has
> >     a pointer to the underlying physical big-block, it also has a
> >     bytes_free field which specifies how many bytes in the underlying
> >     big-block are free.
> >
> >     This is the only tracking done by the blockmap.  It does not actually
> >     try to track WHERE in the big-block the free areas are... figuring
> >     that out will be up to the cleaning code.  What this gives us is the
> >     following:
> >
> >     * Extremely fast freeing of on-disk storage elements.  The target
> >       physical block doesn't have to be read or written, only the governing
> >       blockmap entry.  With 8MB big-blocks and 32-byte blockmap entries one
> >       16K buffer can track 4GB worth of underlying storage, which means
> >       that freeing large amounts of sparse information does not cause the
> >       disk to seek all over the place.
> >
>
> *snip*
>
> Struggling today with a situation wherein 82 Giga-bytes of data were
> moved into an IMAP trash folder on UFS2, outrunning inodes, names et al
> before disk space (plenty of that left) and a cleanup that gets:
>
> /bin/rm: Argument list too long
>
> Unless I script it into manageable chunks....
>
> If HAMMER fs has a better, even mechanism - even a rahter BFBI one, to
> handle that sort of need for massive deletions, it will make a convert here.
>
> Bill
>
>
>
>
>


-- 
Adrian Chadd - adrian@freebsd.org