disk transfer speed problem

[lonely wolf]

initial data: one brand new intel bonham motherboard (i815) , 900 MHz
celeron processor
2 new 80 GB Seagate Barracuda used as raid1, 7200 RPM,ext3 filesystem,
RedHat 2.4.9-21 kernel from  RH 7.2 updates.

settings (identical for hdc and hdd), as detected by the kernel (except
for I/O support  =  3):
#hdparm /dev/hdc
 multcount    = 16 (on)
 I/O support  =  3 (32-bit w/sync)
 unmaskirq    =  0 (off)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 nowerr       =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 23989/16/63, sectors = 156301488, start = 0

#hdparm -i /dev/hdc

 Model=ST380021A, FwRev=3.05, SerialNo=3HV080KH
 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
 RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
 BuffType=unknown, BuffSize=2048kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=-66060037, LBA=yes, LBAsects=156301488
 IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes: pio0 pio1 pio2 pio3 pio4
 DMA modes: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5

 #dmesg|grep UDMA
hda: 14668290 sectors (7510 MB) w/418KiB Cache, CHS=913/255/63, UDMA(66)
(this is the boot disk)

hdc: 156301488 sectors (80026 MB) w/2048KiB Cache, CHS=155061/16/63,
UDMA(100
hdd: 156301488 sectors (80026 MB) w/2048KiB Cache, CHS=155061/16/63,
UDMA(100)

The IDE cables have 80 wires. I am not sure that they are ATA100, but I
think they do.

The problem:
#/sbin/hdparm -tTf /dev/hdd

/dev/hdd:
 Timing buffer-cache reads:   128 MB in  1.17 seconds =109.40 MB/sec
 Timing buffered disk reads:  64 MB in  3.24 seconds = 19.75 MB/sec

Even after issuing raidstop and umounting the partition placed on the
RAID, the speed does not exceed 22 MB/sec.

With hdparm -c1 performances are almost identical

Tests were performed in initlevel 3, with NFS started, but no one but
root  using the machine (from console). In production, the speed is also
very, very slow

Any idea what might limit the transfer speed ?

--
      Manuel Wolfshant       linux registered user #131416
       network administrator    NoBug Consulting Romania
             Beware the fury of a patient man.