Re: Best way to duplicate HDs

[Russell Coker <russell@coker.com.au>]

On Tue, 1 Jan 2002 09:13, Jeff Waugh wrote:
> <quote who="Jason Lim">
>
> > What do you think would be the best way to duplicate a HD to another
> > (similar sized) HD?
>
> dd, using a large buffer size for reasonable performance

I've just done some tests on that with 33G partitions of 46G IDE drives.  The 
drives are on different IDE buses, and the CPU is an Athlon 800.

It seems that a buffer size of 4K (page size on Intel) is much better than 
the default of 512b (no surprise there).  However a buffer size of 1M uses 
more system time than 4K and gives the same elapsed time.  So it seems to me 
that page size is probably a good buffer size to use.

# time dd if=/dev/discs/disc0/part6 of=/dev/discs/disc1/part6
dd: reading `/dev/discs/disc0/part6': Input/output error
67376544+0 records in
67376544+0 records out

real    61m59.876s
user    1m6.110s
sys     13m46.200s
# time dd if=/dev/discs/disc0/part6 of=/dev/discs/disc1/part6 bs=4k
dd: reading `/dev/discs/disc0/part6': Input/output error
8422068+0 records in
8422068+0 records out

real    44m56.078s
user    0m5.350s
sys     5m28.270s
# time dd if=/dev/discs/disc0/part6 of=/dev/discs/disc1/part6 bs=1024k
dd: reading `/dev/discs/disc0/part6': Input/output error
32898+1 records in
32898+1 records out

real    44m55.056s
user    0m0.170s
sys     7m46.130s

-- 
http://www.coker.com.au/bonnie++/     Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/       Postal SMTP/POP benchmark
http://www.coker.com.au/projects.html Projects I am working on
http://www.coker.com.au/~russell/     My home page