--On Wednesday, December 15, 2004 13:38 +0100 Marcin Owsiany <porridge@debian.org> wrote:
On Wed, Dec 15, 2004 at 02:40:37AM -0700, Michael Loftis wrote:Additionally Linux uses 128K disk I/O blocks, if you've built your RAID array with any other size stripe you may suffer pathological performance loss.Do you mean that that driver uses such blocks, or that linux generally uses 128K blocks?
Linux does. That's it's target size. Fibre Channel it's bigger though (256K I believe). Lots of lower end controllers can't do stripes bigger than 64K, which means you do two block writes for every one that Linux does in a best case world. You're also doing two sets of parity calculations, you don't double the amount of time there, but it is increased.