Windows<->VMS Samba performance issue

BG - Ben Armstrong BArmstrong at dymaxion.ca
Fri Sep 17 19:49:04 GMT 2004


OK, now for the server end of things:

A weekend upgrade is scheduled, so here are current and after-upgrade
versions:

On Fri, 2004-09-17 at 14:04 -0500, John E. Malmberg wrote:
> VMS version?

OpenVMS 7.3-1 (upgrade will bring this up to 7.3-1 on Monday).

> TCPIP platform and version?

TCPIP V5.3 ECO 4 (upgrade will bring this up to V5.4 ECO 2 on Monday)

> Samba version?

2.2.8-20040908 (no change on Monday)

> There is one key difference in how some Microsoft Windows clients treat
> large files and how SAMBA does.  SAMBA sends the file sequentially from
> start to finish.  For some unknown reason, Microsoft Windows sends the
> first part of the file, skips a bit and sends the middle, and then backfills.

Our benchmark routine would prevent that sort of copying, wouldn't it?
It simply writes a stream of blocks sequentially.

> And it just may be a case where SAMBA to SAMBA transfers are more efficient
> than WINDOWS to SAMBA transfers, since you would expect that if it were
> really a server issue, that the server would perform badly for both clients.

A factor of 10X more efficient?  I'm as inclined as the next Linux-
hugging geek to glibly say "well, Windows sucks, what do you expect?"
but that's a pretty huge discrepancy!  That's what leads me to believe
it is simply a matter of things not being tuned optimally for Windows to
Samba communication, and yes, probably at the client end, but I don't
believe we can rule out the server out of hand.

> If you use a LINUX SAMBA server instead of a VMS SAMBA server, do you see
> the same difference in performance?

When I use a Linux Samba server, the numbers for the Windows client are
as follows:

C: (Local)          ~0 sec
H: (WinXP)          ~2 sec
G: (Linux Samba)   ~15 sec
S: (OpenVMS Samba) ~76 sec

And considering that the Linux Samba server is my own workstation, which
is only a PII/400 with an old 4G ATA-33 drive, not a server-class
system, I can certainly understand the slower performance than the WinXP
server.  But the OpenVMS Samba server figure is way out there.

I can't compare performance here with a networked Linux client, because
my workstation is the sole Linux system here.

The socket options for the Linux server are:

socket options = IPTOS_LOWDELAY TCP_NODELAY SO_SNDBUF=4096 SO_RCVBUF=4096

The socket options for the VMS server are the defaults.  I don't know
how to examine those.  The conf file doesn't list any.

Ben



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