I have the same problem as here:
161793-software-raid-1-way-too-slow

But I don't know what to check on the log files.

cat /proc/mdstat
Code:
Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4] 
md0 : active raid1 sdb1[1] sda1[0]
      1464843648 blocks [2/2] [UU]
mdadm --detail /dev/md0 gives:
Code:
/dev/md0:
        Version : 00.90.03
  Creation Time : Fri Oct 21 20:50:48 2011
     Raid Level : raid1
     Array Size : 1464843648 (1396.98 GiB 1500.00 GB)
  Used Dev Size : 1464843648 (1396.98 GiB 1500.00 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Thu Nov 10 05:04:10 2011
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : cf297b8c:35bb5a35:6c25913b:c0261e4e
         Events : 0.12

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1
hdparm -tT /dev/sda1

Code:
/dev/sda1:
 Timing cached reads:   332 MB in  2.01 seconds = 165.31 MB/sec
 Timing buffered disk reads:   98 MB in  3.08 seconds =  31.87 MB/sec
hdparm -tT /dev/sda1
Code:
/dev/sdb1:
 Timing cached reads:   346 MB in  2.01 seconds = 172.12 MB/sec
 Timing buffered disk reads:  128 MB in  3.03 seconds =  42.26 MB/sec

hdparm -tT /dev/md0
Code:
/dev/md0:
 Timing cached reads:   330 MB in  2.01 seconds = 164.51 MB/sec
 Timing buffered disk reads:   76 MB in  3.06 seconds =  24.84 MB/sec

Code:
/sbin/hdparm -t /dev/md0

/dev/md0:
 Timing buffered disk reads:   38 MB in  3.34 seconds =  11.39 MB/sec
/sbin/hdparm -t /dev/sda1

/dev/sda1:
 Timing buffered disk reads:  124 MB in  3.03 seconds =  40.99 MB/sec
/sbin/hdparm -t /dev/sdb1

/dev/sdb1:
 Timing buffered disk reads:  180 MB in  3.02 seconds =  59.61 MB/sec

Why is my raid so slow?

What should I check.

Thanks.
Derry