> 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. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
