On Sun, Jul 24, 2011 at 11:34 PM, Phil Harrison <philha...@gmail.com> wrote:
> What kind of performance would you expect from this setup? I know we can > multiple the base IOPS by 24 but what about max sequential read/write? > You should have a theoretical max close to 144x single-disk throughput. Each raidz3 has 6 "data drives" which can be read from simultaneously, multiplied by your 24 vdevs. Of course, you'll hit your controllers' limits well before that. Even with a controller per JBOD, you'll be limited by the SAS connection. The 7k3000 has throughput from 115 - 150 MB/s, meaning each of your JBODs will be capable of 5.2 GB/sec - 6.8 GB/sec, roughly 10 times the bandwidth of a single SAS 6g connection. Use multipathing if you can to increase the bandwidth to each JBOD. Depending on the types of access that clients are performing, your cache devices may not be any help. If the data is read multiple times by multiple clients, then you'll see some benefit. If it's only being read infrequently or by one client, it probably won't help much at all. That said, if your access is mostly sequential then random access latency shouldn't affect you too much, and you will still have more bandwidth from your main storage pools than from the cache devices. -B -- Brandon High : bh...@freaks.com
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