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Date:      Sun, 10 Jun 2001 20:20:21 -0700
From:      Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>
To:        franco@extreme-ware.com
Cc:        stable@FreeBSD.ORG
Subject:   Re: 4.x stable & large NFS services 
Message-ID:  <200106110320.f5B3KnU20896@cwsys.cwsent.com>
In-Reply-To: Your message of "Sun, 10 Jun 2001 20:13:32 PDT." <GMEMLAAKKFHEAODHLBPOCEDCCAAA.franco@extreme-ware.com> 

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In message <GMEMLAAKKFHEAODHLBPOCEDCCAAA.franco@extreme-ware.com>, 
"Franco Gasp
erino" writes:
> 
>   Hello list,
> 
>   I'm in the process of creating a large NFS system for exporting mail
> spools (Maildir) to several frontend mail servers, and wanted to know about
> potential issues to look for. The system will be a dual p3 with a lot of ram
> and hardware raid, and i'm testing fbsd 4.3 vs linux 2.4 for NFS sharing.
> I'm concerned about SMP (not speed, but stability) on fbsd, and am looking
> for honest advice on which use. I will be running my own tests on each, but
> look forward to input from the list.

Linux mounts its filesystems async so to keep the comparison fair you 
will either have to mount your NFS exported filesystems async or use 
softupdates.  Softupdates will give you the reliability of Synchronous 
Metadata (SMD) writes with almost the performance (3% loss) as async 
mounts.

Linux breaks the NFS protocol by notifying the client that writes have 
completed even though they have not, i.e. the write has been completed 
to the buffer cache but not the disk.  This can greatly improve 
performance.  To perform the same asynchronous NFS writes on FreeBSD 
you will need to set sysctl MIB vfs.nfs.async to 1.

Additionally, levelling the playing field by using the same hardware 
configurations on both machines and networks should give you data you 
can analyse.


Regards,                         Phone:  (250)387-8437
Cy Schubert                        Fax:  (250)387-5766
Team Leader, Sun/Alpha Team   Internet:  Cy.Schubert@osg.gov.bc.ca
Open Systems Group, ITSD, ISTA
Province of BC



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