Re: disk transfer speed problem

[Stephen Samuel <samuel@bcgreen.com>]

Picking nits, perhaps -- but after giving us data on hdc,
you did the test on hdd.  I realize you said that it is identical
for both, but if you missed something critical, we'll never see it.

lonely wolf wrote:
> 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.
> 
> 
> 
> 
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-- 
Stephen Samuel +1(604)876-0426                samuel@bcgreen.com
		   http://www.bcgreen.com/~samuel/
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