I think you should test 2 or more disks at the same time. This would prove that your system can or can't move more than about 60MB/s. My old P3-500 SMP can move at least 150MB/s. But I have 3 SCSI buses and 3 PCI buses. Guy > -----Original Message----- > From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- > owner@xxxxxxxxxxxxxxx] On Behalf Of Ming Zhang > Sent: Thursday, June 30, 2005 10:16 PM > To: Linux RAID > Subject: raid0 low performance > > I meet some strange low performance when run RAID0 with vanilla kernel > 2.4.27/2.6.11.12. > > My box is a 2.8G P4 and 1G RAM. 8 400GB SATA disk and A marvel 8port > controller. I run marvel 3.4.1 driver. I wrote a small program to write > device sequentially and SYNCHRONOUSLY. > > This is performance of 1 disk. looks fine. > > 1048576Bytes * 1024 : 55.466MB/s > 524288Bytes * 2048 : 55.830MB/s > 262144Bytes * 4096 : 55.782MB/s > 131072Bytes * 8192 : 55.567MB/s > 65536Bytes * 16384 : 55.926MB/s > 32768Bytes * 32768 : 54.344MB/s > 16384Bytes * 65536 : 41.415MB/s > 8192Bytes * 65536 : 26.499MB/s > 4096Bytes * 65536 : 15.110MB/s > 2048Bytes * 65536 : 8.422MB/s > 1024Bytes * 65536 : 4.318MB/s > > But when run 2 disk raid0, there is only 10% improvement. > > md3 : active raid0 sdb[1] sda[0] > 781422592 blocks 64k chunks > 1048576Bytes * 1024 : 67.300MB/s > 524288Bytes * 2048 : 66.796MB/s > 262144Bytes * 4096 : 65.728MB/s > 131072Bytes * 8192 : 65.017MB/s > 65536Bytes * 16384 : 59.223MB/s > 32768Bytes * 32768 : 49.766MB/s > 16384Bytes * 65536 : 39.162MB/s > 8192Bytes * 65536 : 26.386MB/s > 4096Bytes * 65536 : 15.084MB/s > 2048Bytes * 65536 : 8.383MB/s > 1024Bytes * 65536 : 4.303MB/s > > And when use 4 disks, the speed is slower! > md0 : active raid0 sdh[3] sdg[2] sdf[1] sde[0] > 1562845184 blocks 64k chunks > 1048576Bytes * 1024 : 58.032MB/s > 524288Bytes * 2048 : 56.994MB/s > 262144Bytes * 4096 : 58.289MB/s > 131072Bytes * 8192 : 65.999MB/s > 65536Bytes * 16384 : 59.723MB/s > 32768Bytes * 32768 : 50.061MB/s > 16384Bytes * 65536 : 38.689MB/s > 8192Bytes * 65536 : 26.169MB/s > 4096Bytes * 65536 : 15.169MB/s > 2048Bytes * 65536 : 8.378MB/s > 1024Bytes * 65536 : 4.287MB/s > > > Any hint on this? > > * I do not know how to check current PCI bus speed and I am not sure > whether is limited by that. It is a 64bit card but I am not sure if it > is run at 66MHZ. Should be, but want to check to make sure. > * I tested each disk and all disk performs OK. > > > Thanks > > > Ming - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
