Scott Meilicke wrote: > Obviously iSCSI and NFS are quite different at the storage level, and I > actually like NFS for the flexibility over iSCSI (quotas, reservations, > etc.)
Another key difference between them is that with iSCSI, the VMFS filesystem (built on the zvol presented as a block device) never frees up unused disk space. Once ESX has written to a block on that zvol, it will always be taking up space in your zpool, even if you delete the .vmdk file that contains it. The zvol has no idea that the block is not used any more. With NFS, ZFS is aware that the file is deleted, and can deallocate those blocks. This would be less of an issue if we had deduplication on the zpool (have ESX write blocks of all-0 and those would be deduped down to a single block) or if there was some way (like the SSD TRIM command) for the VMFS filesystem to tell the block device that a block is no longer used. --Joe _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
