On Wed, Apr 7, 2010 at 12:09 PM, Jason S <j.sin...@shaw.ca> wrote: > I was actually already planning to get another 4 gigs of ram for the box > right away anyway, but thank you for mentioning it! As there appears to be a > couple ways to "skin the cat" here i think i am going to try both a 14 > spindle RaidZ2 and 2 X 7 RaidZ2 configuration and see what the performance > is like. I have a fews days of grace before i need to have this server ready > for duty. > > Don't bother with the 14-drive raidz2. I can attest to just how horrible the performance is for a single, large, raidz2 vdev is: atrocious. Especially when it comes time to scrub or resilver. You'll end up thrashing all the disks, taking close to a week to resilver a dead drive (if you can actually get it to complete), and pulling your hair out is frustration.
Our original configuration in our storage servers used a single 24-drive raidz2 vdev using 7200 RPM SATA drives. Worked, not well, but it worked ... until the first drive died. After 3 weeks, the resilver still hadn't finished, the backups processes weren't completing overnight due to the resilver process, and things just went downhill. We redid the pool using 3x raidz2 vdevs using 8 drives each, and things are much better. (If I had to re-do it again today, I'd use 4x raidz2 vdevs using 6 drives each.) The more vdevs you can add to a pool, the better the raw I/O performance of the pool will be. Go with lots of smaller vdevs. With 14 drives, play around with the following: 2x raidz2 vdevs using 7 drives each 3x raidz2 vdevs using 5 drives each (with two hot-spares, or a mirror vdev for root?) 4x raidz2 vdevs using 4 drives each (with one hot-spare, perhaps?) 4x raidz1 vdevs using 4 drives each (maybe not enough redundancy?) 5x mirror vdevs using 3 drives each (maybe too much lost space for redundancy?) 7x mirror vdevs using 2 drives each You really need to decide which is more important: raw storage space or raw I/O throughput. They're almost (not quite, but almost) mutually exclusive. > Something i forgot to note in my original post is the performance numbers i > am concerned with are going to be during reads primarily. There could be at > any one point 4 media players attempting to stream media from this server. > The media players all have 100mb interfaces so as long i can can reliable > stream 400mb/s it should be ok (this is assuming all the media players were > playing high bitrate Blueray streams at one time). Any writing to this array > would happen pretty infrequently and i normally schedule any file transfers > for the wee hours of the morning anyway. > > -- Freddie Cash fjwc...@gmail.com
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