Messages in this thread | | | Subject | WD Raptor/SATA with RAID0 way to slow | From | Julien Oster <> | Date | Fri, 31 Oct 2003 03:49:10 +0100 |
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Hello,
I recently purchased an Asus A7N8X mainboard with the Silicon Imaging SATA controller online and two Western Digital Raptor SATA harddrives with 10krpm.
Those harddisks are supposed to be "really fast", but I don't really get the performance out of them. In fact, I get much less performance than with my "standard consumer" IBM DeskStars.
Besides the WD Raptors, I have two IBM DeskStars (normal PATA). The two IBM deskstars and the two WD Raptors are bundled to linux softraids with RAID level 0 each.
I use the same hdparm command line for all drives during boot, which is:
hdparm -c 1 -m 16 -S 241 -u 1 -k 1 -K 1
I first used a simple hdparm -t on the harddisks individually to see how they perform alone. Here's the values I got for one of the IBMs:
IBM DeskStar Timing buffered disk reads: 64 MB in 1.41 seconds = 45.39 MB/sec
And now for the Raptors: WD Raptor Timing buffered disk reads: 64 MB in 1.24 seconds = 51.61 MB/sec
Well, at least it's faster. But the next test is really annoying me. I did the same hdparm -t on the RAID0 containing the IBMs (/dev/md5) and the one containing the Raptors (/dev/md6) and got the following result:
/dev/md5: Timing buffered disk reads: 64 MB in 0.71 seconds = 90.14 MB/sec
/dev/md6: Timing buffered disk reads: 64 MB in 1.06 seconds = 60.38 MB/sec
For the IBMs, the value is fine, it's nearly double the throughput than with a single drive. But for the Raptor RAID, it's even less than for the IBM RAID! It doesn't even come close to doubling the throughput, which is the fact for the IBM drives.
Another quick test with bonnie++ showed that the Raptor RAID really is slower then the IBM RAID. Not much, but it is - and that despite the fact that it should be much faster. The Raptors have a very low avg read seek time of 4.5ms while the IBMs do have 9.8ms, so I expected at least the filesystem test with bonnie++ to show some performance improvement, when doing things like creating and deleting files, but absolutely no test didn't gave a lower performance for the Raptors.
Any idea of what could be wrong? This really annoys me, because I purchased the smaller Raptors just because I need something as fast as possible, due to the extensive data amounts I'm working it (and SCSI not being an option for my development machine at home).
Thanks in advance, Julien - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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