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Date:      Tue, 30 Dec 2008 15:21:22 +0000
From:      Vincent Hoffman <vince@unsane.co.uk>
To:        Bernard Dugas <bernard@dugas-family.org>
Cc:        Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>, freebsd-questions@freebsd.org
Subject:   Re: Optimising NFS for system files
Message-ID:  <495A3C72.5070802@unsane.co.uk>
In-Reply-To: <495A3957.9050002@dugas-family.org>
References:  <20081216094719.EDCEE1065675@hub.freebsd.org>	<495930E4.1030501@dugas-family.org>	<20081229230115.F68805@wojtek.tensor.gdynia.pl>	<4959DFEF.5090407@dugas-family.org>	<20081230150507.U87347@wojtek.tensor.gdynia.pl> <495A3957.9050002@dugas-family.org>

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Bernard Dugas wrote:
> Wojciech Puchar wrote:
>>> So you din't think that if all files are already in RAM on server, i
>>> will save the drive access time ?
>>
>> FreeBSD automatically use all free memory as cache.
>
> OK
>
> > there is slowdown because network introduces slight delay,
> > but few ms at most if network is made properly
>
> This is a Gbps network with only 1 switch between nfs server and
> client, with less than 0.2ms ping. So bandwidth should not be a
> problem, seems that NFSV3 is the limitation...
>
> Trying to change mtu, but don't look easy, where can i find the
> possible range for ports ?
>
MTU can be a pain, check what your switch supports, and the manpage for
your network driver should say what MTU the nic supports.
mtu is set using ifconfig (or the ifconfig_$nic line in rc.conf) :
from man ifconfig
mtu n   Set the maximum transmission unit of the interface to n, default
             is interface specific.  The MTU is used to limit the size of
             packets that are transmitted on an interface.  Not all
interfaces
             support setting the MTU, and some interfaces have range
restric-
             tions.
from man em  (for example)
     Support for Jumbo Frames is provided via the interface MTU setting.
     Selecting an MTU larger than 1500 bytes with the ifconfig(8)
utility con-
     figures the adapter to receive and transmit Jumbo Frames.  The maximum
     MTU size for Jumbo Frames is 16114.



Vince
> Best regards,




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