There are *lots* of options for configuring a Thumper, what you choose really depends on the kind of performance you want. I found these sites incredibly helpful in working out what was best for us:
http://blogs.sun.com/relling/entry/zfs_raid_recommendations_space_performance http://lindsay.at/blog/archive/2007/04/15/zfs-performance-models-for-a-streaming-server.html One point to remember is that read & write performance are two different things, and are affected in different ways by the disk layout. You also have to consider how many hot spares you want, and whether you want to use a single or dual parity scheme. Based on the posts above I put together a table with estimated read & write performance for several dual parity configurations. Bear in mind these are only estimated figures based on what I learnt in the threads above, but I believe they give a reasonable estimate of physical disk performance. Also bear in mind that while you gain performance by adding Raid sets, you also loose more disks and hence capacity. My full table shows hot spares, drives lost to raid parity and total capacity available, but I'm not going to try to replicate all that here. RAID-Z2 Disks per set.....Sets.....Write Performance.....Read Performance.....Read IOPS 46................1........44....................1....................75 23................2........42....................2....................150 14................3........36....................3....................225 11................4........36....................4....................300 9.................5........35....................5....................375 7.................6........30....................6....................450 6.................7........28....................7....................525 *probably optimum with 6 controllers. 5.................9........27....................9....................675 Dual Parity Mirrored 15................3........15....................45...................3375 *Our preferred configuration The dual parity mirrored set is very tempting for us, you loose a lot of space (only 7.5TB available instead of 22.5TB), but the Thumper is big cheap enough to get away with that, and for us, small random reads are likely to be what we need. However, all this is theoretical and we plan to test the extreme cases and our favoured configurations with real world data before we decide on a final layout. This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
