We run our IMAP spool on ZFS that's derived from LUNs on a Netapp filer. There's a great deal of churn in e-mail folders, with messages appearing and being deleted frequently. I know that ZFS uses copy-on- write, so that blocks in use are never overwritten, and that deleted blocks are added to a free list. This behavior would spread the free list all over the zpool. As well, the Netapp uses WAFL, also a variety of copy-on-write. The LUNs appear as large files on the filer. It won't know which blocks are in use by ZFS. It would have to do copy-on-write each time, I suppose. Do we have a problem here?
The Netapp has a utility that will defragment files on a volume. It must put them back into sequential order. Does ZFS have any concept of the geometry of its disks? If so, regular degragmentation on the Netapp might be a good thing. Should ZFS and the Netapp be using the same blocksize, so that they cooperate to some extent? -- -Gary Mills- -Unix Support- -U of M Academic Computing and Networking- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
