Re: Odd (slow) RAID performance

2006-12-19 Thread Bill Davidsen
Mark Hahn wrote: which is right at the edge of what I need. I want to read the doc on stripe_cache_size before going huge, if that's K 10MB is a LOT of cache when 256 works perfectly in RAID-0. but they are basically unrelated. in r5/6, the stripe cache is absolutely critical in caching

Re: Odd (slow) RAID performance

2006-12-13 Thread Mark Hahn
which is right at the edge of what I need. I want to read the doc on stripe_cache_size before going huge, if that's K 10MB is a LOT of cache when 256 works perfectly in RAID-0. but they are basically unrelated. in r5/6, the stripe cache is absolutely critical in caching parity chunks. in r0,

Re: Odd (slow) RAID performance

2006-12-12 Thread Bill Davidsen
Neil Brown wrote: On Friday December 8, [EMAIL PROTECTED] wrote: I have measured very slow write throughput for raid5 as well, though 2.6.18 does seem to have the same problem. I'll double check and do a git bisect and see what I can come up with. Correction... it isn't 2.6.18 that

Re: Odd (slow) RAID performance

2006-12-12 Thread Raz Ben-Jehuda(caro)
On 12/12/06, Bill Davidsen [EMAIL PROTECTED] wrote: Neil Brown wrote: On Friday December 8, [EMAIL PROTECTED] wrote: I have measured very slow write throughput for raid5 as well, though 2.6.18 does seem to have the same problem. I'll double check and do a git bisect and see what I can come

Re: Odd (slow) RAID performance

2006-12-12 Thread Bill Davidsen
Raz Ben-Jehuda(caro) wrote: On 12/12/06, Bill Davidsen [EMAIL PROTECTED] wrote: Neil Brown wrote: On Friday December 8, [EMAIL PROTECTED] wrote: I have measured very slow write throughput for raid5 as well, though 2.6.18 does seem to have the same problem. I'll double check and do a git

Re: Odd (slow) RAID performance

2006-12-09 Thread Bill Davidsen
Neil Brown wrote: On Friday December 8, [EMAIL PROTECTED] wrote: I have measured very slow write throughput for raid5 as well, though 2.6.18 does seem to have the same problem. I'll double check and do a git bisect and see what I can come up with. Correction... it isn't 2.6.18 that

Re: Odd (slow) RAID performance

2006-12-08 Thread Gabor Gombas
On Thu, Dec 07, 2006 at 10:51:25AM -0500, Bill Davidsen wrote: I also suspect that write are not being combined, since writing the 2GB test runs at one-drive speed writing 1MB blocks, but floppy speed writing 2k blocks. And no, I'm not running out of CPU to do the overhead, it jumps from

Re: Odd (slow) RAID performance

2006-12-07 Thread Bill Davidsen
Dan Williams wrote: On 12/1/06, Bill Davidsen [EMAIL PROTECTED] wrote: Thank you so much for verifying this. I do keep enough room on my drives to run tests by creating any kind of whatever I need, but the point is clear: with N drives striped the transfer rate is N x base rate of one drive;

Re: Odd (slow) RAID performance

2006-12-07 Thread Corey Hickey
Bill Davidsen wrote: Dan Williams wrote: On 12/1/06, Bill Davidsen [EMAIL PROTECTED] wrote: Thank you so much for verifying this. I do keep enough room on my drives to run tests by creating any kind of whatever I need, but the point is clear: with N drives striped the transfer rate is N x base

Re: Odd (slow) RAID performance

2006-12-07 Thread Neil Brown
On Monday December 4, [EMAIL PROTECTED] wrote: Here is where I step into supposition territory. Perhaps the discrepancy is related to the size of the requests going to the block layer. raid5 always makes page sized requests with the expectation that they will coalesce into larger requests

Re: Odd (slow) RAID performance

2006-12-07 Thread Neil Brown
On Friday December 8, [EMAIL PROTECTED] wrote: I have measured very slow write throughput for raid5 as well, though 2.6.18 does seem to have the same problem. I'll double check and do a git bisect and see what I can come up with. Correction... it isn't 2.6.18 that fixes the problem. It is

Re: Odd (slow) RAID performance

2006-12-04 Thread Dan Williams
On 12/1/06, Bill Davidsen [EMAIL PROTECTED] wrote: Thank you so much for verifying this. I do keep enough room on my drives to run tests by creating any kind of whatever I need, but the point is clear: with N drives striped the transfer rate is N x base rate of one drive; with RAID-5 it is about

RE: Odd (slow) RAID performance

2006-12-01 Thread Roger Lucas
Roger Lucas wrote: What drive configuration are you using (SCSI / ATA / SATA), what chipset is providing the disk interface and what cpu are you running with? 3xSATA, Seagate 320 ST3320620AS, Intel 6600, ICH7 controller using the ata-piix driver, with drive cache set to

Re: Odd (slow) RAID performance

2006-12-01 Thread Bill Davidsen
Roger Lucas wrote: Roger Lucas wrote: What drive configuration are you using (SCSI / ATA / SATA), what chipset is providing the disk interface and what cpu are you running with? 3xSATA, Seagate 320 ST3320620AS, Intel 6600, ICH7 controller using the ata-piix driver, with drive cache set to

Odd (slow) RAID performance

2006-11-30 Thread Bill Davidsen
Pardon if you see this twice, I sent it last night and it never showed up... I was seeing some bad disk performance on a new install of Fedora Core 6, so I did some measurements of write speed, and it would appear that write performance is so slow it can't write my data as fast as it is

RE: Odd (slow) RAID performance

2006-11-30 Thread Roger Lucas
-Original Message- From: [EMAIL PROTECTED] [mailto:linux-raid- [EMAIL PROTECTED] On Behalf Of Bill Davidsen Sent: 30 November 2006 14:13 To: linux-raid@vger.kernel.org Subject: Odd (slow) RAID performance Pardon if you see this twice, I sent it last night and it never showed up

Re: Odd (slow) RAID performance

2006-11-30 Thread Bill Davidsen
Roger Lucas wrote: -Original Message- From: [EMAIL PROTECTED] [mailto:linux-raid- [EMAIL PROTECTED] On Behalf Of Bill Davidsen Sent: 30 November 2006 14:13 To: linux-raid@vger.kernel.org Subject: Odd (slow) RAID performance Pardon if you see this twice, I sent it last night and it never

RE: Odd (slow) RAID performance

2006-11-30 Thread Roger Lucas
What drive configuration are you using (SCSI / ATA / SATA), what chipset is providing the disk interface and what cpu are you running with? 3xSATA, Seagate 320 ST3320620AS, Intel 6600, ICH7 controller using the ata-piix driver, with drive cache set to write-back. It's not obvious to me why

Re: Odd (slow) RAID performance

2006-11-30 Thread Bill Davidsen
Roger Lucas wrote: What drive configuration are you using (SCSI / ATA / SATA), what chipset is providing the disk interface and what cpu are you running with? 3xSATA, Seagate 320 ST3320620AS, Intel 6600, ICH7 controller using the ata-piix driver, with drive cache set to