On Wednesday, March 01, 2006 1:16 AM, Mirko Benz wrote: > > As promised we have tested 3 Gb (aka SATA II) disks. > Configuration: LSI SAS3442X controller, Promise SAS JBOD, 12 disks > Seagate SATA 80 GB > > Tested with parallel dd invocations with bs=32k. > The results look better: > > # disks Read AVG Write AVG > 1 69 69,0 68 68,0 > 6 420 70,0 324 54,0 > 7 459 65,6 367 52,4 > 8 426 53,3 394 49,3 > 9 399 44,3 389 43,2 > 10 410 41,0 431 43,1 > 11 438 39,8 428 38,9 > 12 468 39,0 481 40,1 > > Available bandwidth is 4 * 3 Gb = 1.5 GB (4 lanes / external wide SAS > port). > So there is still some room for improvement. Has anyone else > a similar > setup and can provide results? > Maybe with the Adaptec SAS controller? > Sorry, I've not had a chance to replicate this. Of late, I've been overloaded. I asked co-worker regarding this. They told me they believe SATA devices when they open frame, they will complete entire data transaction during a single connection. Meaning they don't do disconnect, and yield to other devices as do SAS devices. Thus could be the reason when you have 12 SATA devices, the performance is low. Jeff Garzik is this true? However, when I have a chance, I will verify this via bus analyzer, and do some testing. I beleive I can obtain about 10 SATA disk. Eric - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
