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Message: 18
Date: Wed, 5 Nov 2003 06:21:04 EST
From: [EMAIL PROTECTED]
Subject: [Samba] Is there a buffer or cache setting in samba?
To: [EMAIL PROTECTED]
Message-ID: [EMAIL PROTECTED]
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Hi.
Can anyone tell me if samba has any settings that determine how much data
gets cached or buffered in RAM before being written to the computer's
hard
drives?
I'm having a strange problem and I suspect that the explanation has to do
with that kind of setting.
I am using a Linux system (P4-3.06 Ghz, 1 GB RAM, 2.4.22 kernel, samba
2.2.8a) to store video and audio files that can be accesssed by a
group of
Windows-based video editing systems. I got the whole system up and
running a week ago
and it was working perfectly (my storage devices, by the way, are a
series of
firewire drives arranged into a RAID 10 array)
When I tested the system with disk testing program on the Windows
side, I
got a transfer rate of 22 MB/sec for a 1 GB test. And in real life, I
could
sustain a rate of at least 18 MB/second for 20 minutes over my gigabit
network.
That's what is required for my application -- digitizing uncompressed
video.
But now things have suddenly fallen apart. Yesterday I had to reinstall
Mandrake 9.2 because I had been moving firewire and ethernet cards
around to
different PCI slots to optimize the system and I just messed things up
too much.
Hmmm, reinstalling is normally not a good solution on unix, and if you
do, it's advisable to at least backup all configuration files (tar -cjvf
/some/safe/place/etc`date +%Y%m%d`.tar.bz2 /etc).
BTW, Mandrake 9.2 has a parallel-installable version of samba-3.0.0
available in contrib:
# urpmi samba3-server
(assuming you have a contrib urpmi medium available, see
http://plf.zarb.org/~nanardon if you don't know how to do this)
Samba3 may perform better than 2.2.x (possibly mainly since sendfile is
enabled by default). Just be careful to only run one at a time (unless
you have been even more careful to set them up to run in parallel).
So
I reinstalled and went back to the same card configuration I had when
I got
the 18 MB/second. And now it doesn't work.
I know that I am using a DIFFERENT smb.conf file now compared to
before. I
don't think I have the old one that I had made with SWAT. The one I'm
using
right now is very simple and it forces a user and group name on all
files written
to the Linux share.
Looking at a Linux monitoring program -- I believe it's called XOSVIEW
- -- I
think I can see the problem.
Yesterday when I tested the system I saw that all the RAM had to fill
up
completely (took about 40 seconds at 18 MB/sec) before Linux started
writing to
the hard drives. And shortly after that my Windows video program would
abort,
telling me the data wasn't getting transferred fast.
Last week, when things were working -- and I was using the same
monitoring
program --Linux would start writing to the drives after about just a
few seconds
rather than buffering or caching so much data in RAM. And I could see
in the
monitoring program that there was more RAM free.
There must be a setting in samba that determines how much data is
cached or
buffered in RAM before writing it to the drives. Do you know anything
about
this?
The only thing (AFAIK) samba does regarding caching is calling sync, see
the 'strict sync' and 'sync always' options). But, this may harm
performance (as the kernel normally has a better idea about when it
should write what to disk than a client program does), but it's worth a
shot. You probably want to try 'strict sync = yes'.
Regards,
Buchan
- --
|--Another happy Mandrake Club member--|
Buchan MilneMechanical Engineer, Network Manager
Cellphone * Work+27 82 472 2231 * +27 21 8828820x202
Stellenbosch Automotive Engineering http://www.cae.co.za
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