raid5 Такая скорость - это нормально?

собрал райд 5
скорость подозрительно маленькая =\


[root@2-fserver ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sda2[0] sdc1[2] sdb1[1]
406476416 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]

unused devices: <none>

===========

/dev/sda:

Model=SAMSUNG HD252KJ , FwRev=CM100-11, SerialNo=S0NJJ1MP600841
Config={ Fixed }
RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4
BuffType=DualPortCache, BuffSize=16384kB, MaxMultSect=16, MultSect=?16?
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=268435455
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5
AdvancedPM=no WriteCache=enabled
Drive conforms to: unknown: ATA/ATAPI-3,4,5,6,7

* signifies the current active mode

/dev/sdb:

Model=SAMSUNG HD252KJ , FwRev=CM100-11, SerialNo=S0NJJ1MP600840
Config={ Fixed }
RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4
BuffType=DualPortCache, BuffSize=16384kB, MaxMultSect=16, MultSect=?16?
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=268435455
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5
AdvancedPM=no WriteCache=enabled
Drive conforms to: unknown: ATA/ATAPI-3,4,5,6,7

* signifies the current active mode

/dev/sdc:

Model=SAMSUNG HD250HJ , FwRev=FH100-05, SerialNo=S0URJADPB22568
Config={ Fixed }
RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4
BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=?16?
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=268435455
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5
AdvancedPM=yes: disabled (255) WriteCache=enabled
Drive conforms to: unknown: ATA/ATAPI-3,4,5,6,7

* signifies the current active mode
=============
[root@2-fserver ~]# hdparm -tT /dev/md0

/dev/md0:
Timing cached reads: 1948 MB in 2.00 seconds = 973.87 MB/sec
Timing buffered disk reads: 152 MB in 3.03 seconds = 50.18 MB/sec
[root@2-fserver ~]# hdparm -tT /dev/sda2

/dev/sda2:
Timing cached reads: 1926 MB in 2.00 seconds = 963.06 MB/sec
Timing buffered disk reads: 122 MB in 3.04 seconds = 40.20 MB/sec
[root@2-fserver ~]# hdparm -tT /dev/sdb1

/dev/sdb1:
Timing cached reads: 2000 MB in 2.00 seconds = 1000.52 MB/sec
Timing buffered disk reads: 126 MB in 3.03 seconds = 41.61 MB/sec
[root@2-fserver ~]# hdparm -tT /dev/sdc1

/dev/sdc1:
Timing cached reads: 1992 MB in 2.00 seconds = 995.98 MB/sec
Timing buffered disk reads: 112 MB in 3.05 seconds = 36.76 MB/sec
======================