I haven't seen much discussion on how deduplication affects performance. I've enabled dudup on my 4-disk raidz array and have seen a significant drop in write throughput, from about 100 MB/s to 3 MB/s. I can't imagine such a decrease is normal.
> # zpool iostat nest 1 (with dedup enabled): > ... > nest 1.05T 411G 91 18 197K 2.35M > nest 1.05T 411G 147 15 443K 1.98M > nest 1.05T 411G 82 28 174K 3.59M > # zpool iostat nest 1 (with dedup disabled): > ... > nest 1.05T 410G 0 787 0 96.9M > nest 1.05T 410G 1 899 253K 95.0M > nest 1.05T 409G 0 533 0 48.5M I do notice when dedup is enabled that the drives sound like they are constantly seeking. iostat shows average service times around 20 ms which is normal for my drives and prstat shows that my processor and memory aren't a bottleneck. What could cause such a marked decrease in throughput? Is anyone else experiencing similar effects? Thanks, James _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
