raid3 is slow

[R. B. Riddick]

--- Szabó Péter <matyee at mail.alba.hu> wrote:
> raid3
> Transfer rates:
>         outside:       102400 kbytes in   1.179933 sec =    86785 kbytes/sec
>         middle:        102400 kbytes in   1.148816 sec =    89135 kbytes/sec
>         inside:        102400 kbytes in   1.171987 sec =    87373 kbytes/sec
>
Looks good...

> #diskinfo -vt /dev/label/nmivol1
>         outside:       102400 kbytes in   1.839020 sec =    55682 kbytes/sec
>         middle:        102400 kbytes in   2.112483 sec =    48474 kbytes/sec
>         inside:        102400 kbytes in   3.416896 sec =    29969 kbytes/sec
>
Looks slow...

> # atacontrol mode ad0
> current mode = UDMA100
> # atacontrol mode ad1
> current mode = UDMA100
> # atacontrol mode ad2
> current mode = UDMA100
> # atacontrol mode ad3
> current mode = UDMA100
> # atacontrol mode ad6
> current mode = SATA150
>
Looks good...

> gstripe may help, and extends disk space, but less secure.
>
Yup...

> #dd if=/dev/zero of=/mnt/new/x.x bs=1m count=128
> 128+0 records in
> 128+0 records out
> 134217728 bytes transferred in 11.410957 secs (11762180 bytes/sec)
>
Hmm

And what if u try this:
  dd if=/dev/raid3/... of=/dev/null bs=1m count=128
?

> > Disks   ad0   ad1   ad2   ad3   ad6                       intrn
> > KB/t   8.42  8.42  8.42  8.42  5.67                113904 buf
> > tps     287   287   287   287  1780                   133 dirtybuf
> > MB/s   2.36  2.36  2.36  2.36  9.85                 69984 desiredvnodes
> > % busy   25    26    24    26    99                 21586 numvnodes
>
8KB/transfer is a little low for my taste... Looks like ur copy program uses
32KB transfers, instead of 128KB transfers...

> > I use mc to copy.
>
What if u try
  dd if=/source-file/on/raid3-device of=/dev/null bs=1m count=128
?

-Arne


 
____________________________________________________________________________________
Don't pick lemons.
See all the new 2007 cars at Yahoo! Autos.
http://autos.yahoo.com/new_cars.html