Re: Linux file copy slowness ??

parvinderb@xxxxxxxxx wrote:
> Hi,
>
> We are trying to copy a 15Gig file from one directory to another (inside
> same partition) for example:
>
> cp /data/BigFile /data/data/ (Bigfile - being file that is greater than
> 15 gig).
>
> It takes about 32 minutes to finish copying. When we do the same
> operation on a windows 2003 server it takes almost HALF the time.
>
> I am wondering if this behaviour is normal or something wrong with
> system?kernel? etc.
>
> The system is a hefty: Dell 1850 server with Dual Xeons 3.2 ghz (hyper
> threaded) with 2 Gig ram, SCSI hard drives 10k rpm.
>
> Also, while the system is copying the file, I don't see any kernel errors
> or IO errros and all the time while the sytem is copying this drive the
> cpu usage is at 50 Any help is highly appreciated.
>
> Forgot to mention on another post: The file system is EXT3 and OS
> -Redhat Enterprise 3
>
Do you have another scsi drive (preferably, but not necessarily on a
different SCSI controller) on the system? If so, it might be faster to copy
to a spare spot on a different drive and then copy it back. This would cut
the seek time dramatically if that is the bottleneck, as it very well might be.

But I have 10,000 rpm hard drives on an Ultra/320 SCSI controller and I have
seen 50MBytes/second transfer rate on working system (also RHEL3) for a
sustained interval (many seconds), but with a full load of other processes
running, messing up the L3 cache on the dual 3.06GHz hyperthreades Xeons,
the disk IO rate can drop to under 15 MBytes/second.

One trick is to ask how you do the copying. If you use _cpio --pass-through_
it might run faster than with the _cp_ command.

--
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