raid0 slower than devices it is assembled of?

[Witold Krecicki <adasi@kernel.pl>]

I've got / on linux-raid0 on 2.6.0-t11-cset-20031209_2107:
<cite>
/dev/md/1:
        Version : 00.90.01
  Creation Time : Thu Sep 11 22:04:54 2003
     Raid Level : raid0
     Array Size : 232315776 (221.55 GiB 237.89 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 1
    Persistence : Superblock is persistent

    Update Time : Mon Dec 15 12:55:48 2003
          State : clean, no-errors
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

     Chunk Size : 64K

    Number   Major   Minor   RaidDevice State
       0       8        3        0      active sync   /dev/sda3
       1       8       19        1      active sync   /dev/sdb3
           UUID : b66633c2:ff11f60d:00119f8d:7bb9fc6c
         Events : 0.357
</cite>
Disks are two ST3120026AS connected to sii3112a controller, driven by sata_sil 
'patched' so no limit for block size is applied (it's not needed for it). 

Those are results of hdparm -tT on drives:
<cite>
/dev/md/1:
 Timing buffer-cache reads:   128 MB in  0.40 seconds =323.28 MB/sec
 Timing buffered disk reads:  64 MB in  1.75 seconds = 36.47 MB/sec
/dev/sda:
 Timing buffer-cache reads:   128 MB in  0.41 seconds =309.23 MB/sec
 Timing buffered disk reads:  64 MB in  1.46 seconds = 43.87 MB/sec
/dev/sdb:
 Timing buffer-cache reads:   128 MB in  0.41 seconds =315.32 MB/sec
 Timing buffered disk reads:  64 MB in  1.23 seconds = 52.04 MB/sec
</cite>
What seems strange to me is that second drive is faster than first one 
(devices are symmetrical, sd[a,b]2 is swapspace (not mounted at time of 
test), sd[a,b]1 is /boot (raid1)).
What is even stranger is that raid0 which should be faster than single drive, 
is pretty much slower- what's the reason of that?
-- 
Witold Kręcicki (adasi) adasi [at] culm.net
GPG key: 7AE20871
http://www.culm.net