Samba writing speed with big blocks

Steve Litt slitt at
Sun Dec 12 21:07:55 GMT 1999

This is just a shot in the dark, but what if you reduce max xmit=? Also,
see what your logs say during the write, and see what tcpdump says during
the write. See what kind of performance FTP has with the big blocks.

Steve Litt

At 02:39 AM 12/13/1999 +1100, Petr Sulla wrote:
>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
>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
>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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