Re: ext3 zerofree option and RedHat back port?

[Ron Yorston <rmy tigress co uk>]

"Ulf Zimmermann" <ulf openlane com> wrote:
>Reason I asked is this. We use currently 3Par S400 and E200 as SAN
>arrays. The new T400 and T800 has a built in chip to do more intelligent
>thin provisioning but I believe even the S400 and E200 we have will free
>on the SAN level a block of a thin provisioned volume if it gets zero'ed
>out. Haven't gotten around yet to test it, but I am planning on. We are
>currently using 3 different file system types, one is a propriety from
>Onstor for their Bobcats (NFS/CIFS heads) where I believe I have
>observed just freeing of SAN level blocks. The two other are EXT3 and
>OCFS2.

Interesting.  A similar case I've seen recently is s3backer, a FUSE
filesystem that keeps its blocks as objects in Amazon S3:

   http://code.google.com/p/s3backer/

Blocks of zeroes aren't actually stored, so they suggest using zerofree
to get rid of non-zero deleted blocks and avoid being charged for them.

Ron