Samba writing speed with big blocks

Petr Sulla xsulla at
Sun Dec 12 15:38:05 GMT 1999

Hello !

I'm having serious problems with Samba's writing speed (both 2.0.5a from
RH 6.1 and 2.0.6 compiled from sources) on a 100Mbit network.

If I write a file with block size 65487 or less, then the writing speed is about
7-8 MB/s - a very nice value, my bow to the Samba team :)

If I change the block size to 65488 or more, then the writing speed falls
down to 3 MB/s, which is not what I expect from a 100Mbit network :\

Samba behaves this way even if SO_RCVBUF and SO_SNDBUF are set to 8192
and "read size" to 16384 and "max xmit" to 16384.

The corresponding part of my smb.conf looks like this:

   client code page = 852
   preserve case = yes
   oplocks = True
   getwd cache = Yes
   null passwords = no
   read raw = yes
   write raw = yes
   read size = 65535
   max xmit = 65535
   deadtime = 15
   strict sync = no
   interfaces =
   remote announce =

The box is a PIII 500Mhz, software RAID5 with read and write throughput of 30MB/s
and 15MB/s. It has RH6.1 installed, with 2.2.13ac3 kernel. The network card
uses the DECchip Tulip driver. FTP reads 9MB/s and writes 7MB/s. The tested
client was W98 SR 1.

This problem is perhaps not very interesting if you only use Explorer or
WinCommander, because they both use block size smaller than 65488. But we
use a special program with greater blocksize... :\

What causes this strange behaviour ? Is there something strange with the
2.2.13 kernel, or the ac3 patch ? What could I do about this ?
Do you experience this too ?

Please help, because my boss already makes unpolite notices about Linux and
threatens with installing NT on the server and I would be quite unhappy if
this would happen.

Yours sincerely
                        Petr Sulla

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