Copy Mb per Sec speed???

[Kevin Lamb]

Hi,

Not sure if anyone can assist in this, but does anyone know what the average copy speed is when using cp.

I have an L2000 with 4x440Mhz CPUs, the data I want to copy from one filesystem to another is 7.1Gb, I am looking for a ball park time so I can organize the down time.

The data is on 2 LUNs on an E12 AutoRaid and the copy will be on the same Raid but over 4LUNs striped.

Cheers,

Kev

[Bill McNAMARA_1]

try iostat

ie
iostat -t 5

Later,
Bill

[Carlos Fernandez Riera]

It will depend on the method you use:

if you use cp all data will pass throug buffer cache. If you use vxfs you can disable cache during cp.

But , if your lvols are of teh same size, it is better( faster) the use of dd command.

use also timex command to get sample time and use it with some methods:


timex cp sample_orig sample_dest

timex dd if=/dev/vg/rlvolsample_orig of=/dev/vg/rlvolsample_dest bs=1024k

....

[Stefan Farrelly · Accepted solution]

The speed of cp is entirely dependant on the speed of the disks you are using. Its not really possible to estimate without testing it first on your configuration.

The best way to test it is to dd the rlvol and output it to /dev/null and time it, eg;
time dd if=/dev/vgXX/rlvolYY of=/dev/null bs=1024k

This will give you a time in seconds to complete the copy, and hopefully your new striped lvol is the same size so you can dd for real when doing the copy. If not you can dd each file individually (which cp would do anyway), eg;
for i in $(ls)
do
dd if=$i of=/dev/null bs=1024k
done

Or use cp instead of dd but cp $i to /dev/null, this will again give you an exact time to copy before you do it for real.

[Kevin Lamb]

Hi,

Thanks for you help, I have just tried the timex and am getting approx 300Mb per Min so the whole area should be copied within 30Mins

Thanks.

Kev