Fwd: [Samba] Memory usage

[John Drescher]

---------- Forwarded message ----------
From: John Drescher <drescherjm at gmail.com>
Date: Aug 21, 2007 10:00 AM
Subject: Re: [Samba] Memory usage
To: rajeev at cracknell.com


> What else does it make the machine slow.
Possibly permissions. Maybe the filesystem choice. It could also be
filename case handling as linux is case sensitive and windows is not.
Are you using ldap or ADS?

> Is it the raid. I have 8 WD SATA
Doubtful.

> HDD with raid ready (3mbps) hard disks on a 8 port 3ware controller.
I have seen complaints of poor performance with 3ware controllers
although I don't have any on my linux systems so I do not know. Do you
have write back cache on?

> Does
> anyone have a comparison on SATA raid and SAS raid disk. As you know SAS
> disk are very expensive I would like to know from experts in the list who
> can tell me which of the following is best.
>
> 1) 2 servers each having 2.0TB raid disk with SAS drives, 2GB ram and
> standard other features.
> 2) 4 No servers with 1TB each with 2GB ram and standard other features.
>
I can't compare that as I have never had a SAS. My servers are home
built machines with 1.2 to 3TB of software raid (mostly 6)  with 2GB
to 4GB of ram all running 64 bit gentoo and have 1 or 2 Opteron
processors.

>
> If the projects are distributed in the 2 option do you think it would be
> better than 1 sty?.  as you know the price of SATA disk is much cheaper than
> the SAS disk and we could nearly by 4 servers for that money.
>
I have 10TB of linux software raid5 and raid6 using dozens of SATA
disks on a nearly 100% gigabit network with about 100 machines and
most of this data is accessed via samba. I have seen a few speed
problems but for the most part all works smoothly. One case of a speed
problem is a DICOM scrubbing application that reads up to 100,000
512KB files off one server, removes patient info from the headers and
stores this data on a second server. In normal conditions this
operation is about 5 to 10 of these files per second but at times this
slows to 1 per second. When this happens I see on the samba server
that the samba process is taking > 25% of the CPU time (which it never
does when it is working) so after stopping this scrubbing process and
kill the offending smbd process all is well again.

John


-- 
John M. Drescher