On Sat, Jan 14, 2006 at 01:40:53AM -0500, Mark Hahn wrote: > > Initially, we were getting 'hdparm -t' numbers around 80MB/s, but this > > was when we were testing /dev/sdb1 - the (only) partition on the device. > > When we started testing /dev/sdb, it increased significantly to around > > 180MB/s. I'm not sure what to conclude from this. > > there are some funny interactions between partitions, filesystems > and low-level parameters like readahead. Hmmm, I'm not convinced, though it could be that the disks in my workstation are not fast enough. I used hdparm and your iorate program to compare the performance on my fastest disk (7200rpm, ATA100). The difference between partition vs. disk is definitely within the margin of error: 2-3MB/sec when I'm averaging around 50MB/sec. I'd be suspicious of much more difference between the two... > I'm about to test an 8x 3ware 9550 this weekend. but 4x disks on a $US 60 > promise tx2 will already beat your system ;) No way. Cause you're gonna max the PCI bus if you use that card with MD. Say you're running on a 66MHz PCI bus, you'll max at 266MB/sec. For four disks, 266/4 = 66.5MB/sec, you're already slower than the original poster's RAID. Add network traffic to that equation, and Promise is laughable. The 3Ware will rock considerably, as it's real hardware, so you'll only send one copy of the data. On top of which, the PCIX will be hard to fill up. I've seen 32-bit, 33MHz 3Ware cards hold 80MB/sec without breaking a sweat. If there's a PCI-X or PCI Express version of the TX4, then just pretend I didn't post this ::-) -- Ross Vandegrift ross@xxxxxxxxxxxx "The good Christian should beware of mathematicians, and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of Hell." --St. Augustine, De Genesi ad Litteram, Book II, xviii, 37 - 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
