Something else came to mind which is a negative regarding deduplication. When zfs writes new sequential files, it should try to allocate blocks in a way which minimizes "fragmentation" (disk seeks). Disk seeks are the bane of existing storage systems since they come out of the available IOPS budget, which is only a couple hundred ops/second per drive. The deduplication algorithm will surely result in increasing effective fragmentation (decreasing sequential performance) since duplicated blocks will result in a seek to the master copy of the block followed by a seek to the next block. Disk seeks will remain an issue until rotating media goes away, which (in spite of popular opinion) is likely quite a while from now.
Someone has to play devil's advocate here. :-) Bob ====================================== Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
