Richard Elling wote: > Define "fragmentation"? Maybe this is the wrong thread. I have noticed that an old pool can take 4 hours to scrub, with a large portion of the time reading from the pool disks at the rate of 150+ MB/s but zpool iostat reports 2 MB/s read speed. My naive interpretation is that the data scrub is looking for has become fragmented.
Should I refresh the pool by zfs sending it to another pool then zfs receiving the data back again, the same scrub can take less than an hour with zpool iostat reporting more sane throughput. On an old pool which had lots of snapshots come and go, the scrub throughput is awful. On that same data, refreshed via zfs send/receive, the throughput much better. It would appear to me that this is an artifact of fragmentation, although I have nothing scientific on which to base this. Additional unscientific observations leads me to believe these same "refreshed" pools also perform better for non-scrub activities. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
