I've recently set up new Linux based file server. The distribution I'm using is Ubuntu 10.10. I've created two software raid devices as follows:
mc@vmr:~$ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid1 sdf1[1] sdh1[3] sde1[0] sdg1[2] 19530688 blocks [4/4] [UUUU] md1 : active raid10 sdh3[3] sdf3[1] sde3[0] sdg3[2] 1912461184 blocks 64K chunks 2 near-copies [4/4] [UUUU] Device /dev/md0 (raid1) is mounted on "/" and /dev/md1 (raid10) is mounted on "/home". Unfortunately the performance of my raid10 is deeply unsatisfying. Here is the performance of each single HDD:
mc@vmr:~$ sudo hdparm -t /dev/sdh3 /dev/sdh3: Timing buffered disk reads: 410 MB in 3.00 seconds = 136.57 MB/sec mc@vmr:~$ sudo hdparm -t /dev/sdf3 /dev/sdf3: Timing buffered disk reads: 402 MB in 3.01 seconds = 133.60 MB/sec mc@vmr:~$ sudo hdparm -t /dev/sde3 /dev/sde3: Timing buffered disk reads: 418 MB in 3.01 seconds = 139.10 MB/sec mc@vmr:~$ sudo hdparm -t /dev/sdg3 /dev/sdg3: Timing buffered disk reads: 406 MB in 3.00 seconds = 135.32 MB/sec So naturally I was expecting read performance around 260 MB/sec, but instead I've got this:
mc@vmr:~$ sudo hdparm -t /dev/md1 /dev/md1: Timing buffered disk reads: 172 MB in 3.04 seconds = 56.64 MB/sec Firstly I've assumed that hdparm testing method is not to be 100% trusted so I did kind of real-world read test and performance was still not as expected (random.bin is placed on raid10):
mc@vmr:~$ dd if=random.bin of=/dev/null bs=256k 38800+0 records in 38800+0 records out 10171187200 bytes (10 GB) copied, 96.3874 s, 106 MB/s Lastly I would like to share that the read performance of raid1 is exactly as expected:
mc@vmr:~$ sudo hdparm -t /dev/md0 /dev/md0: Timing buffered disk reads: 412 MB in 3.01 seconds = 136.91 MB/sec Has anyone came across problem like this? Any clues?
