On Wed, Dec 22, 2010 at 8:27 AM, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote: > Rogier Wolff <R.E.Wolff@xxxxxxxxxxxx> writes: > >> Unquoted text below is from either me or from my friend. >> >> >> Someone suggested we try an older kernel as if kernel 2.6.32 would not >> have this problem. We do NOT think it suddenly started with a certain >> kernel version. I was just hoping to have you kernel-guys help with >> prodding the kernel into revealing which component was screwing things >> up.... > [...] >> ata3.00: ATA-8: WDC WD10EARS-00Y5B1, 80.00A80, max UDMA/133 > > This is an "Advanced format" drive, which, in this case, means it > internally has a 4KB sector size and exports a 512byte logical sector > size. ÂIf your partitions are misaligned, this can cause performance > problems. > >> MDstat: >> >> Personalities : [raid1] [raid6] [raid5] [raid4] >> md125 : active raid5 sdd3[5](S) sdb3[4] sda3[0] sdc3[3] >> Â Â Â 3903488 blocks super 1.1 level 5, 512k chunk, algorithm 2 [3/3] [UUU] >> >> md126 : active raid5 sda4[0] sdd4[3] sdc4[5](S) sdb4[4] >> Â Â Â 1910063104 blocks super 1.1 level 5, 512k chunk, algorithm 2 >> [3/3] [UUU] >> >> md1 : active raid5 sda2[0] sdd2[3](S) sdb2[1] sdc2[4] >> Â Â Â 39067648 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] >> [3/3] [UUU] >> >> md1 : active raid5 sda2[0] sdd2[3](S) sdb2[1] sdc2[4] >> Â Â Â 39067648 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] >> [UUU] > > A 512KB raid5 chunk with 4KB I/Os? ÂThat is a recipe for inefficiency. > Again, blktrace data would be helpful. > > Cheers, > Jeff I am late to this thread but I'd like to give a +1 to everything Jeff said. I tried to build many different mdadm RAID configurations using the WD10EARS. They simply didn't work. There were huge delays and mdadm would take drives off line. It was a mess. First, the drives are 4K sector so it's really important to get them on the right partition boundary. Installing Gentoo requires that we un-tar some large-ish files. IIRC on a 512 byte boundary these drives took 20-30 minutes to do this. On a 4K boundary they took about 1 minute. I know that doesn't make sense but those were my numbers, and it's a very high end Intel i7-980x MB so there wasn't any other problem I could find. Even when I got that part worked out I found that the drives just didn't work well in a RAID. The mdadm list led me to believe that the root cause was the lack of TLER in the firmware. I don't know how to show that's true or not... When all that was determined I dropped RAID and I still ran into Load Count issue that's discussed elsewhere in this thread. I then bought 5 WD RAID Edition drives and everything works perfectly. > 100MB/Sec on RAID1 and about 180MB/S on RAID0. Overall the WD10EARS drives were very disappointing, at least as shipped. I have 5 of them sitting here unused. I would like to find some time to try them again one of these days but I don't have high hopes. Cheers, Mark -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
