Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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  
 Timing buffered disk reads:  410 MB in  3.00 seconds = 136.57 MB/sec

mc@vmr:~$ sudo hdparm -t /dev/sdf3
 Timing buffered disk reads:  402 MB in  3.01 seconds = 133.60 MB/sec

mc@vmr:~$ sudo hdparm -t /dev/sde3
 Timing buffered disk reads:  418 MB in  3.01 seconds = 139.10 MB/sec

mc@vmr:~$ sudo hdparm -t /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
 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
 Timing buffered disk reads:  412 MB in  3.01 seconds = 136.91 MB/sec

Has anyone came across problem like this? Any clues?

share|improve this question
Could you do some filesystem benchmarks on both partitions and post the results? The commands below will run iozone in automatic mode with a test file twice as large as the amount of RAM you have. FILESIZE=$(awk '/MemTotal/ {printf("%dg\n", $2 / 1024 / 1024 * 2)}' /proc/meminfo); iozone -a -n $FILESIZE -f /root/tempfile > /tmp/raid1_benchmark; iozone -a -n $FILESIZE -f /home/tempfile > /tmp/raid10_benchmark; – sciurus Mar 1 '11 at 16:43

64K chunks

— way too small. Almost every I/O op. has noticeable probability to involve 2 disks with such stripe size, which means more wasted I/O. My suggestion is at least 512 KiB and may be 1—2 MiB.

Also, you might find that mine answer useful.

share|improve this answer

I just created again my md1 array :

leo@stellie:~$ cat /proc/mdstat 
Personalities : [raid1] [raid10] 
md1 : active raid10 sdc6[0] sdb6[2] sda6[1]
      32807040 blocks super 1.2 64K chunks 2 far-copies [3/3] [UUU] 
md0 : active raid1 sda1[0] sdb1[2] sdc1[1]
      248896 blocks [3/3] [UUU]

Notice that : 1. metadata version was upgraded to 1.2 2. far-copies instead of near-copies

leo@stellie:~$ sudo hdparm -t /dev/md1
 Timing buffered disk reads: 372 MB in  3.02 seconds = 123.29 MB/sec

I made some more hdparm test while the array was not yet in use and : - 64K chunks and near-copies performed better than before (~70MB/sec) - 512K chunks had lower transfer rate (~50MB/sec) - max read performance has been reached with far-copies and 64K chunks

As you said, I need to perform a test with iozone as well.

share|improve this answer

There are few options

1.There a problem with:

  • hard drive firmware
  • firmware motherboard
  • firmware sata controller
  • bug in ubuntu

2.try tuning a few things

  • hdparm -t --direct /dev/md0
  • blockdev --setra 16384
  • try bigger block with raid10 (not sure if its any good)

anyway hdparm is not really the best benchmark software - try bonni++ ,iozone or dd

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.