* Arjen van der Meijden: > The disadvantage of using Areca or 3Ware is obviously the lack of > support in A-brand servers and the lack of support for SAS-disks. Only > recently Areca has stepped in the SAS-market, but I have no idea how > easily those controllers are integrated in standard servers (they tend > to be quite large, which will not fit in 2U and maybe not even in 3U > or 4U-servers). Recent 3ware controllers are a bit on the hot side, too. We had to switch from two 12 port controllers to a single 24 port controller because of that (combined with an unlucky board layout: the two 8x PCIe connectors are next to each other). Unfortunately, read performance maxes out at about 8 disks in a RAID-10 configuration. Software RAID-0 across hardware RAID-1 is significantly faster (factor of 3 to 5 in low-level benchmarks). However, it seems that something in this stack does not enforce write barriers properly, so I don't think we will use this in production. RAID-6 doesn't perform well, either (especially for several processes reading different files sequentially). We'll probably split the 24 disks into a couple of RAID-10s, and distribute tables and indexes manually among the file systems. This is a bit disappointing, especially because the system is able to read at 800+ MB/s, as shown by the software-RAID-on-hardware-RAID configuration. I haven't seen 24-disk benchmarks with Areca controllers. A comparison might be interesting. -- Florian Weimer <fweimer@xxxxxx> BFK edv-consulting GmbH http://www.bfk.de/ Kriegsstraße 100 tel: +49-721-96201-1 D-76133 Karlsruhe fax: +49-721-96201-99 ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
