Re: mismatch_cnt questions
On 00:21, H. Peter Anvin wrote: I have just updated the paper at: http://www.kernel.org/pub/linux/kernel/people/hpa/raid6.pdf ... with this information (in slightly different notation and with a bit more detail.) There's a typo in the new section: s/By assumption, X_z != D_n/By assumption, X_z != D_z/ Regards Andre -- The only person who always got his work done by Friday was Robinson Crusoe signature.asc Description: Digital signature
Issue with Adaptec AIC-7899P using MD on Dell PE 2650
Hi, I'm happily using MD on one of our fileservers. This fileserver is basically a Dell PowerEdge 2650 loaded with 5x300GB HDDs. A 1TB Raid5 partition is defined over the 5 disks md1 : active raid5 sdb3[5] sde3[4] sdd3[3] sdc3[2] sda3[0] 1170238464 blocks level 5, 64k chunk, algorithm 2 [5/4] [U_UUU] Today, one of the HDDs failed: I got a lot of errors like this one in the logs raid5:md1: read error not correctable (sector 153334912 on sdb3). I failed/removed the disk from the array mdadm /dev/mdX -f /dev/sdbX mdadm /dev/mdX -r /dev/sdbX I then removed it from the scsi bus echo /proc/scsi/scsi Removed the disk from the server (phisically) Inserted a new one Did rescan the SCSI bus to detect the new HDD, and the server froze. This is the second time it happens while changing a hard disk on that particular brand/model. Is this a known issue with the SCSI HBA? Did i do something wrong ? Thanks Laurent - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
sw raid0 read bottleneck
Hi! I am currently testing 3ware raid cards. Now i have 15 disks, and on these a swraid0. The write speed seems good (700 MBps), but the read performance only 350 MBps. Another problem when i try to read with two process, then the _sum_ of the read speeds fall back to 200 MBps. So there is a bottleneck, or something i need to know, but i dont have ideas. The details: /dev/md0: Version : 00.90.03 Creation Time : Tue Mar 13 16:57:32 2007 Raid Level : raid0 Array Size : 7325797440 (6986.43 GiB 7501.62 GB) Raid Devices : 15 Total Devices : 15 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Tue Mar 13 16:57:32 2007 State : clean Active Devices : 15 Working Devices : 15 Failed Devices : 0 Spare Devices : 0 Chunk Size : 64K # uname -a Linux ursula 2.6.18-4-686-bigmem #1 SMP Wed Feb 21 17:30:22 UTC 2007 i686 GNU/Linux # xfs_info /mnt/ meta-data=/dev/md0 isize=256agcount=32, agsize=57232784 blks = sectsz=512 attr=0 data = bsize=4096 blocks=1831449088, imaxpct=25 = sunit=16 swidth=240 blks, unwritten=1 naming =version 2 bsize=4096 log =internal bsize=4096 blocks=32768, version=1 = sectsz=512 sunit=0 blks realtime =none extsz=983040 blocks=0, rtextents=0 (all software Debian Etch) four Intel(R) Xeon(TM) CPU 3.00GHz two 3ware 9590SE-8ML on PCIe Intel Corporation 5000P Chipset -- Tomka Gergely, [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: sw raid0 read bottleneck
On Tue, 13 Mar 2007, Tomka Gergely wrote: Hi! I am currently testing 3ware raid cards. Now i have 15 disks, and on these a swraid0. The write speed seems good (700 MBps), but the read performance only 350 MBps. Another problem when i try to read with two process, then the _sum_ of the read speeds fall back to 200 MBps. So there is a bottleneck, or something i need to know, but i dont have ideas. The details: /dev/md0: Version : 00.90.03 Creation Time : Tue Mar 13 16:57:32 2007 Raid Level : raid0 Array Size : 7325797440 (6986.43 GiB 7501.62 GB) Raid Devices : 15 Total Devices : 15 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Tue Mar 13 16:57:32 2007 State : clean Active Devices : 15 Working Devices : 15 Failed Devices : 0 Spare Devices : 0 Chunk Size : 64K # uname -a Linux ursula 2.6.18-4-686-bigmem #1 SMP Wed Feb 21 17:30:22 UTC 2007 i686 GNU/Linux # xfs_info /mnt/ meta-data=/dev/md0 isize=256agcount=32, agsize=57232784 blks = sectsz=512 attr=0 data = bsize=4096 blocks=1831449088, imaxpct=25 = sunit=16 swidth=240 blks, unwritten=1 naming =version 2 bsize=4096 log =internal bsize=4096 blocks=32768, version=1 = sectsz=512 sunit=0 blks realtime =none extsz=983040 blocks=0, rtextents=0 (all software Debian Etch) four Intel(R) Xeon(TM) CPU 3.00GHz two 3ware 9590SE-8ML on PCIe Intel Corporation 5000P Chipset -- Tomka Gergely, [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Have you tried increasing your readahead values for the md device? - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: sw raid0 read bottleneck
On Tue, 13 Mar 2007, Justin Piszcz wrote: Have you tried increasing your readahead values for the md device? Yes. No real change. According to my humble mental image, readahead not a too useful thing, when we read 1-4 thread with sdd. The io subsystem already reading with the possible maximum speed, so don't have time to read ahead. Correct me, if i wrong. -- Tomka Gergely, [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: sw raid0 read bottleneck
On Tue, 13 Mar 2007, Tomka Gergely wrote: On Tue, 13 Mar 2007, Justin Piszcz wrote: Have you tried increasing your readahead values for the md device? Yes. No real change. According to my humble mental image, readahead not a too useful thing, when we read 1-4 thread with sdd. The io subsystem already reading with the possible maximum speed, so don't have time to read ahead. Correct me, if i wrong. I was wrong, readahead can speed things up, to 450 MBps. -- Tomka Gergely, [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: sw raid0 read bottleneck
Nice. On Tue, 13 Mar 2007, Tomka Gergely wrote: On Tue, 13 Mar 2007, Tomka Gergely wrote: On Tue, 13 Mar 2007, Justin Piszcz wrote: Have you tried increasing your readahead values for the md device? Yes. No real change. According to my humble mental image, readahead not a too useful thing, when we read 1-4 thread with sdd. The io subsystem already reading with the possible maximum speed, so don't have time to read ahead. Correct me, if i wrong. I was wrong, readahead can speed things up, to 450 MBps. -- Tomka Gergely, [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: sw raid0 read bottleneck
On Tuesday March 13, [EMAIL PROTECTED] wrote: On Tue, 13 Mar 2007, Tomka Gergely wrote: On Tue, 13 Mar 2007, Justin Piszcz wrote: Have you tried increasing your readahead values for the md device? Yes. No real change. According to my humble mental image, readahead not a too useful thing, when we read 1-4 thread with sdd. The io subsystem already reading with the possible maximum speed, so don't have time to read ahead. Correct me, if i wrong. I was wrong, readahead can speed things up, to 450 MBps. Can you tell use what read-ahead size you needed? 15 drives and 64K chunks gives 960K per stripe. The raid0 code should set the read-ahead to twice that: 1920K which I would have thought would be enough, but apparently not. Thanks, NeilBrown - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: sw raid0 read bottleneck
On Wed, 14 Mar 2007, Neil Brown wrote: On Tuesday March 13, [EMAIL PROTECTED] wrote: On Tue, 13 Mar 2007, Tomka Gergely wrote: On Tue, 13 Mar 2007, Justin Piszcz wrote: Have you tried increasing your readahead values for the md device? Yes. No real change. According to my humble mental image, readahead not a too useful thing, when we read 1-4 thread with sdd. The io subsystem already reading with the possible maximum speed, so don't have time to read ahead. Correct me, if i wrong. I was wrong, readahead can speed things up, to 450 MBps. Can you tell use what read-ahead size you needed? 15 drives and 64K chunks gives 960K per stripe. The raid0 code should set the read-ahead to twice that: 1920K which I would have thought would be enough, but apparently not. blockdev --setra 262144 /dev/md0 gives me 650+ MB/s with 4 threads (paralell running sdd). Lower values give lower speeds, greater values not giving higher speeds. -- Tomka Gergely, [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mismatch_cnt questions
Andre Noll wrote: On 00:21, H. Peter Anvin wrote: I have just updated the paper at: http://www.kernel.org/pub/linux/kernel/people/hpa/raid6.pdf ... with this information (in slightly different notation and with a bit more detail.) There's a typo in the new section: s/By assumption, X_z != D_n/By assumption, X_z != D_z/ Thanks, fixed. -hpa - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
