ext3 zerofree option and RedHat back port?

Ulf Zimmermann ulf at openlane.com
Wed Sep 24 03:22:09 UTC 2008

> -----Original Message-----
> From: Eric Sandeen [mailto:sandeen at redhat.com]
> Sent: 09/23/2008 10:02
> To: Theodore Tso
> Cc: Ulf Zimmermann; ext3-users at redhat.com
> Subject: Re: ext3 zerofree option and RedHat back port?
> Theodore Tso wrote:
> > On Tue, Sep 23, 2008 at 10:13:20AM -0500, Eric Sandeen wrote:
> >> Ulf Zimmermann wrote:
> >>> Can anyone tell me if the zerofree option for ext3 has been back
> ported
> >>> to RedHat EL4 or EL5?
> >> there appears to be no backporting to do; it's a single .c file
> >> makes simple use (I assume...) of libext2...
> >>
> >> But no, it's not in Fedora, EPEL, or RHEL.  Builds fine on my rhel5
> box.
> >>
> >> If you wanted to, you could be the maintainer for Fedora, and put
> >> into EPEL, which would make it available for RHEL :)
> >
> > Or it would be roughly a 5 line change to e2image (3 for option
> > parsing, 1 for the usage line, and 1 to the if statement in
> > write_raw_image_file() :-) to add an option to extend the "raw dump"
> > functionality to also dump the data blocks of files, at which point
> it
> > would create a sparse file containing only the used blocks in the
> > filesystem for you, automatically.
> >
> >     	 	       		      	   - Ted
> hey that sounds even better than a random collection of single-purpose
> utilities!  ;)
> (But I suppose the original util had the other useful purpose of
> scrubbing free blocks even if you don't intend to compress the fs
> image...)
> -Eric

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

Ulf Zimmermann

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