Slowdown when copying large files

[Michael Anthon]

I am currently investigating using samba on a Linux box to provide file
server services on our NT LAN (I'm a bit sick of NT doing dummy spits on
me).  I'm running RH5.1, and have just upgraded samba to
samba-1.9.18p8-51.3 (using the rpm from
http://samba.anu.edu.au/samba/ftp/Binary_Packages/redhat/RPMS/5.1/samba-
1.9.18p8-51.3.i386.rpm)

The setup includes several NT servers, one set up as a PDC and 2 BDCs
and samba is confiigured to use the PDC for password authentication.

Everything seems to work fine, except that when I try copying a largeish
file (the test one I'm using is about 12M) it takes about 8-10 minutes
to copy (this is on a 10M LAN).  I ran top on the Linux box while I was
doing this and smbd seems to start off using around 8% of CPU time, but
at the point things seem to start slowing down, the usage jumps up to
75-80%.

I'm wondering if this is a known problem and if it's not, perhaps a few
pointers on where to start looking might help me a bit.

TIA
Michael Anthon

TAMS Systems


PS.  
I have done a bit more checking.  It seems that when I start to copy a
large file, smbd starts using about 5% CPU time.  This slowly increases
to a point where it is using about 80% or so.  At the same time, the
system seems to start thrashing the hard drive.  I did look in to the
memory issues.  My swap file had been disabled (no entry in fstab ??)
but I have since re-enabled it and that has not improved matters at all
(it's not actually using the swap anyway since it has 64M of RAM and
it's not full yet).

I'm totally stumped.

I originally posted this to the NT-Dom list and got this reply.....

> -----Original Message-----
> From: David Bannon [mailto:D.Bannon at latrobe.edu.au]
> Sent: Friday, 24 July 1998 5:07
> To: Multiple recipients of list
> Subject: Re: Slowdown when copying large files
> 
> 
> At 04:33 PM 24/07/1998 +1000, Michael Anthon wrote:
> >Everything seems to work fine, except that when I try 
> copying a largeish
> >file (the test one I'm using is about 12M) it takes about 
> 8-10 minutes
> >to copy (this is on a 10M LAN).
> 
> 
> I have RH5.0 running on an old 586-100 with 32 meg ram. (I 
> use it for a
> range of 'odd jobs'). I just copied a 14meg file to its IDE 
> drive in 1m
> 16sec using samba. And this was from another network drive on 
> another system.
> 
> I wonder if your system is lacking a bit of memory or some 
> other resource ?
> 
> Might be a good question to ask on the regular samba/linux channels.
> 
> David
> ------------------------------------------------------------
> David Bannon                      D.Bannon at latrobe.edu.au
> School of Biochemistry            Phone 61 03 9479 2197
> La Trobe University, Plenty Rd,   Fax   61 03 9479 2467
> Bundoora, Vic, Australia, 3083    http://bioserve.latrobe.edu.au
> ------------------------------------------------------------
> .... Humpty Dumpty was pushed !
>