We have customers using dedup with lots of vm images... in one extreme case they are getting dedup ratios of over 200:1!
You don't need dedup or sparse files for zero filling. Simple zle compression will eliminate those for you far more efficiently and without needing massive amounts of ram. Our customers have the ability to access our systems engineers to design the solution for their needs. If you are serious about doing this stuff right, work with someone like Nexenta that can engineer a complete solution instead of trying to figure out which of us on this forum are quacks and which are cracks. :) Tim Cook <t...@cook.ms> wrote: >On Wed, May 4, 2011 at 10:23 PM, Edward Ned Harvey < >opensolarisisdeadlongliveopensola...@nedharvey.com> wrote: > >> > From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- >> > boun...@opensolaris.org] On Behalf Of Ray Van Dolson >> > >> > Are any of you out there using dedupe ZFS file systems to store VMware >> > VMDK (or any VM tech. really)? Curious what recordsize you use and >> > what your hardware specs / experiences have been. >> >> Generally speaking, dedup doesn't work on VM images. (Same is true for ZFS >> or netapp or anything else.) Because the VM images are all going to have >> their own filesystems internally with whatever blocksize is relevant to the >> guest OS. If the virtual blocks in the VM don't align with the ZFS (or >> whatever FS) host blocks... Then even when you write duplicated data >> inside >> the guest, the host won't see it as a duplicated block. >> >> There are some situations where dedup may help on VM images... For example >> if you're not using sparse files and you have a zero-filed disk... But in >> that case, you should probably just use a sparse file instead... Or ... >> If >> you have a "golden" image that you're copying all over the place ... but in >> that case, you should probably just use clones instead... >> >> Or if you're intimately familiar with both the guest & host filesystems, >> and >> you choose blocksizes carefully to make them align. But that seems >> complicated and likely to fail. >> >> >> >That's patently false. VM images are the absolute best use-case for dedup >outside of backup workloads. I'm not sure who told you/where you got the >idea that VM images are not ripe for dedup, but it's wrong. > >--Tim > >_______________________________________________ >zfs-discuss mailing list >zfs-discuss@opensolaris.org >http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
