comment below... On Feb 12, 2010, at 2:25 PM, TMB wrote: > I have a similar question, I put together a cheapo RAID with four 1TB WD > Black (7200) SATAs, in a 3TB RAIDZ1, and I added a 64GB OCZ Vertex SSD, with > slice 0 (5GB) for ZIL and the rest of the SSD for cache: > # zpool status dpool > pool: dpool > state: ONLINE > scrub: none requested > config: > > NAME STATE READ WRITE CKSUM > dpool ONLINE 0 0 0 > raidz1 ONLINE 0 0 0 > c0t0d0 ONLINE 0 0 0 > c0t0d1 ONLINE 0 0 0 > c0t0d2 ONLINE 0 0 0 > c0t0d3 ONLINE 0 0 0 > [b] logs > c0t0d4s0 ONLINE 0 0 0[/b] > [b] cache > c0t0d4s1 ONLINE 0 0 0[/b] > spares > c0t0d6 AVAIL > c0t0d7 AVAIL > > capacity operations bandwidth > pool used avail read write read write > ---------- ----- ----- ----- ----- ----- ----- > dpool 72.1G 3.55T 237 12 29.7M 597K > raidz1 72.1G 3.55T 237 9 29.7M 469K > c0t0d0 - - 166 3 7.39M 157K > c0t0d1 - - 166 3 7.44M 157K > c0t0d2 - - 166 3 7.39M 157K > c0t0d3 - - 167 3 7.45M 157K > c0t0d4s0 20K 4.97G 0 3 0 127K > cache - - - - - - > c0t0d4s1 17.6G 36.4G 3 1 249K 119K > ---------- ----- ----- ----- ----- ----- ----- > I just don't seem to be getting any bang for the buck I should be. This was > taken while rebuilding an Oracle index, all files stored in this pool. The > WD disks are at 100%, and nothing is coming from the cache. The cache does > have the entire DB cached (17.6G used), but hardly reads anything from it. I > also am not seeing the spike of data flowing into the ZIL either, although > iostat show there is just write traffic hitting the SSD: > > extended device statistics cpu > device r/s w/s kr/s kw/s wait actv svc_t %w %b us sy wt id > sd0 170.0 0.4 7684.7 0.0 0.0 35.0 205.3 0 100 11 8 0 82 > sd1 168.4 0.4 7680.2 0.0 0.0 34.6 205.1 0 100 > sd2 172.0 0.4 7761.7 0.0 0.0 35.0 202.9 0 100 > sd3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 > sd4 170.0 0.4 7727.1 0.0 0.0 35.0 205.3 0 100 > [b]sd5 1.6 2.6 182.4 104.8 0.0 0.5 117.8 0 31 [/b]
iostat has a "n" option, which is very useful for looking at device names :-) The SSD here is perfoming well. The rest are clobbered. 205 millisecond response time will be agonizingly slow. By default, for this version of ZFS, up to 35 I/Os will be queued to the disk, which is why you see 35.0 in the "actv" column. The combination of actv=35 and svc_t>200 indicates that this is the place to start working. Begin by reducing zfs_vdev_max_pending from 35 to something like 1 to 4. This will reduce the concurrent load on the disks, thus reducing svc_t. http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#Device_I.2FO_Queue_Size_.28I.2FO_Concurrency.29 -- richard > Since this SSD is in a RAID array, and just presents as a regular disk LUN, > is there a special incantation required to turn on the Turbo mode? > > Doesnt it seem that all this traffic should be maxing out the SSD? Reads from > the cache, and writes to the ZIL? I have a seocnd identical SSD I wanted to > add as a mirror, but it seems pointless if there's no zip to be had.... > > help? > > Thanks, > Tracey > -- > This message posted from opensolaris.org > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
