See the reads on the pool with the low I/O ? I suspect reading the DDT causes the writes to slow down.
See this bug http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6913566. It seems to give some backgrounds. Can you test setting the "primarycache=metadata" on the volume you test ? This would be my initial test. My suggestion would be that it may improve the situation because your ARC can be better utilized for DDT (this does not make much sence for production without a SSD cache, because you practially disable all caches for reading without a L2ARC (aka SSD)!) As I read the bug report above - it seems the if the DDT (deduplication table) does not fit into memory or dropped from there the DDT has to be read from disk causing massive random I/O. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
