On 26/02/14 06:55, Jakob Unterwurzacher wrote:
Dear list, I am seeing a strange performance issue on a 4 x 4TB md raid6 on kernel 3.12. Initial resync goes nice and fast at 130MB/s:# cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] md1 : active raid6 sda3[0] sdd3[3] sdc3[2] sdb3[1] 7751269376 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU] [=>...................] resync = 7.5% (293925504/3875634688) finish=458.4min speed=130210K/sec md0 : active raid1 sda2[0] sdd2[3] sdc2[2] sdb2[1] 29280128 blocks super 1.2 [4/4] [UUUU] unused devices: <none>...unless the ext4 filesystem on the array is mounted read-write! Then, speed plummets to 1 - 7MB/s. The filesystem is empty and totally idle; a simple "mount -o remount,ro" restores the speed to 130MB/s.
You are probably expeririencing an effect of this : http://www.thomas-krenn.com/en/wiki/Ext4_Filesystem#Lazy_Initialization Regards, 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
