-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Le 09/07/2010 01:37, Edward Ned Harvey a écrit : >> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- >> boun...@opensolaris.org] On Behalf Of Philippe Schwarz >> . > But if you're impressed with performance by enabling writeback, you can > still do better ... > > The most effective thing you could possibly do is to disable the writeback, > and add SSD for log device. ZFS is able to perform in this configuration, > better than the WriteBack. And in this situation, surprisingly, enabling > the WriteBack actually hurts performance slightly. > .
Hi, i bought a little SSD (OCZ Agility 30GB) and added half to L2ARC and second half to ZIL: zpool add zfsda1 log da3s2 zpool add zfsda1 cache da3s1 zpool status pool: zfsda1 state: ONLINE scrub: none requested config: NAME STATE READ WRITE CKSUM zfsda1 ONLINE 0 0 0 da1 ONLINE 0 0 0 logs ONLINE 0 0 0 da3s2 ONLINE 0 0 0 cache da3s1 ONLINE 0 0 0 errors: No known data errors OK, let's try to burst the write (WC disabled on the Raid controller) ... Result is ...awful! A `zpool iostat -v 1` shows: - - Although the L2ARC (da3s1) is showed separately from the pool, the ZIL (da3s2) is shown within the pool. Is it the normal behaviour ? - - ZIL seems to be quiet almost all the time and burst sometimes. OK, i may the normal behaviour of a cache. capacity operations bandwidth pool used avail read write read write - ---------- ----- ----- ----- ----- ----- ----- zfsda1 2.36G 694G 0 176 0 21.8M da1 2.36G 694G 0 56 0 6.88M da3s2 128K 15.0G 0 119 0 15.0M cache - - - - - - da3s1 3.06G 11.7G 0 0 0 0 - ---------- ----- ----- ----- ----- ----- ----- But, at the end of the copy process (copy a 1GB file from & to the same pool), the used capacity of the ZIL remains unchanged... Puzzling.. - - And ,last but not least... the copy isn't faster at all! - -- Without ZIL&L2ARC time cp /zfsda1/rnd /zfsda1/rn2 real 3m23.297s - -- With ZIL&L2ARC time cp /zfsda1/rnd /zfsda1/rn2 real 3m34.847s Should i call my (dummy) test into question ? Thanks. Best regards. - -- Lycée Maximilien Perret, Alfortville -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkw5m0UACgkQlhqCFkbqHRZf1ACgkMIz6gf+H4bXfK5GH1HkWwag WPgAn2H6/j344LdFEOiig3MAxEy68yG2 =Mjn9 -----END PGP SIGNATURE----- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss