[Samba] Marginal write performance & pauses in outgoing transfers -Possible bug

[Marian Mlcoch, Ing]

Test you transfer from samba location?
If not try use smbclient to connect w2k and test transfer.
Second test is Another clean W2k station test.

Possible this can be a problem with kernel oplock, oplocks and level2
combination this is aplied when file is reading from samba disk but when
writing to samba maybe not used with fast speed.

Bye.

----- Original Message ----- 
From: "Nicolas Gieczewski" <nicolas at nixsoftware.com>
To: <samba at lists.samba.org>
Sent: Saturday, July 26, 2003 3:36 PM
Subject: [Samba] Marginal write performance & pauses in outgoing
transfers -Possible bug


> Hello everybody,
>
> I have a FreeBSD 4.8-STABLE server running Samba 2.2.8a and a workstation
> running Windows 2000 SP4. Whereas FTP transfers between these boxes
average
> 700 KB/s (10 mbps LAN) in both directions, Samba transfers are exhibiting
> this odd behavior:
>
> Windows 2000 --> Samba = 700 KB/s (perfect)
> Samba --> Windows 2000 = 100 KB/s (terrible, inconsistent, with LONG
pauses)
>
> Trust me, I have tried *everything* I've run into as far as tuning goes,
> so please don't ask if I've tuned up my stuff or request my configuration
> file :)  If this were a configuration-related issue, performance should be
> the same no matter in which direction data is transferred. Nevertheless,
> I have really tried everything that exists. Furthermore, I remember I
didn't
> have this problem with certain older version of Samba before I upgraded
> my ports (unfortunately I don't remember which version it was, but I don't
> really want to downgrade).
>
> The problem lies in the fact that outgoing transfers are not consistent
and
> undergo VERY long, random pauses. My hub's activity LED shows that, during
> a transfer from Samba to Win2k, no packets are transferred about 70% of
the
> time. Yep, only during about 30% of the total time a transfer takes is
there
> actual network activity--the remaining 70% of the time is wasted on random
> (both length-and interval-wise) pauses. When transferring the other way
> around, though (Win2k --> Samba), it's just as fast as FTP (because I *do*
> have my stuff properly tuned!), so fast in fact that it makes my hub's
> excessive bandwidth alert LED go on ;)
>
> All my network cards are propery configured, both media- and duplex- wise.
> There are no collissions. I don't even know why I'm saying this, because
the
> rates I can achieve with FTP both ways alone proves that Samba is the
> culprit.
>
> Because most of the time a transfer takes to complete is wasted on those
> random pauses, anything I could tune concerning buffer sizes and the like
is
> almost useless because it only takes effect while data is actually being
> transferred, not during the pauses. I have fiddled with buffer sizes and,
by
> looking at the hub's activity light, I could (visually and easily) see how
> more or less data was transferred in between the pauses depending on the
> buffer sizes I chose. However, the pauses stayed consistent throughout all
> my tests. By using larger buffer sizes, all I could do was push more data
> through in between the pauses, but my tuning never affected the length or
> interval of the pauses themselves. Buffer sizes are not the only thing I
> fiddled with, and anyway, this was the same configuration file I had been
> using with that older version of Samba that didn't have this problem, and
> nothing changed in between.
>
> And again, the pretty good rate (for a 10 mbps LAN) I can achieve in
> the Win2k --> Samba scenario proves that there's nothing wrong with
> my configuration.
>
> Does anyone happen to know what could be causing this? I ran into a post
> on the FreeBSD net mailing list posted a long time ago by someone who had
> this same problem, but his difference between read and write performance
> was much bigger, and that was an ancient version of Samba which had
> certain wait flag turned on in the code. However, that was supposed to be
> off by default in future versions.
>
> Please advice!
>
> Thanks in advance,
>
> Nicolas Gieczewski
> Nix Software Solutions
> http://www.nixsoftware.com/
>
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