> -----Original Message----- > From: Eric Sandeen [mailto:sandeen@xxxxxxxxxx] > Sent: 09/23/2008 20:30 > To: Ulf Zimmermann > Cc: Theodore Tso; ext3-users@xxxxxxxxxx > Subject: Re: ext3 zerofree option and RedHat back port? > > Ulf Zimmermann 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. > > Ok, so you really want to zero the unused blocks in-place, and e2image > writing out a new sparsified image isn't a ton of help. > > The tool does that, I guess - but only on an unmounted or RO-mounted > filesystem, right? (plus I'd triple-check that it's doing things > correctly, opening a block device and splatting zeros around, one hopes > that it is!) > > But in any case the util itself is simple enough that building (or even > packaging) for fedora/EPEL should be trivial. > > (FWIW, there is work upstream for filesystems to actually communicate > freed blocks to the underlying storage, just for this purpose...) > > -Eric I am going to try it out by hand. Create a thin provisioned volume, write random crap to it, then zero the blocks. See if that shrinks the physical allocated space. Ulf. _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
