Roger, thanks for your reply. > If the hardware setup cannot do faster than 35 MB/second nothing you can do > will make it go faster. On a straight read of any of the disks, using dd or 'hdparm -t', I can get about 70MB/sec to 75MB/sec out of the disk drives. I've always thought that the MD software deliberately 'throttled' a resync/recover operation, slowing things down if the disks were being used by applications, so I've been happy with around 35MB/sec for my resyncs, as the system has usually been lightly loaded with other programs using the drives. > What kind of motherboard is it and which chipset is on that MB, and what > kind of sata ports are the disks on? > > If you can get all 3 disks in the machine and working (without a resync) > then I would try doing "dd if=/dev/sda of=/dev/null bs=1M" for each of the 3 > disks at the same time and see if that causes a hang, if it does it is not a > MD issue, also I would check the speed of 1 disk, 2 disks, and 3 disks and > see how bad those ports bottleneck with multiple disks being used. My system is 7 months old; the motherboard is a Gigabyte GA-P35-DS4. It has an Intel ICH9R northbridge with 6 SATA 2 ports and a 'Gigabyte' (JMicron 20360/20363) southbridge with 2 SATA 2 ports. I have two 500GB Western Digital SATA 2 internal disks, one on each controller, in an MD raid1 mirror. I've experienced these problems while plugging in a third Western Digital 500GB drive into the ICH9R controller and adding it as a third mirror element to the raid1 MD device. Other than this 'hang' problem with MD I've never had a problem with any of the disks. For example, after yesterday failing to synchronise the third disk with the MD raid1 device, I proceeded to do a filesystem-level copy, using cpio to copy all the files from the MD device to the (separately mounted) third disk. That worked fine (took a lot longer, though, because of the huge number of small files I have on the filesystem). A follow-up rsync to 'catch' files that had been modified during the cpio also succeeded. I just now ran a dd test as you suggested of each disk, and each ran fine, with dd reporting speeds of 66.1, 68.6 and 70.5 MB/s. One 'hard resetting link' error/event was logged for one of the three SATA 2 ports without the dd process for that link seeing any error. I saw absolutely no such errors logged at all with my 'hang' problems in synchronising the raid1 device yesterday. Everything would proceed fine until the resync operation simply stopped - with /sys/block/md1/md/sync_completed static, showing no further progress - and the system then 'hanging' on anything that tried to access a disk. Brad -- 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
