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Date:      Fri, 06 Feb 2009 18:27:18 +0100
From:      Joe7 <admin@kedvenc.hu>
To:        Rick Macklem <rmacklem@uoguelph.ca>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: nfs delay causing broken files
Message-ID:  <20090206182718.dhsvxzt7r4sswos4@www.site.hu>
In-Reply-To: <Pine.GSO.4.63.0902061222020.14142@muncher.cs.uoguelph.ca>
References:  <20090205212511.jrmipmazeo4o0c8w@www.site.hu> <Pine.GSO.4.63.0902061126100.6236@muncher.cs.uoguelph.ca> <Pine.GSO.4.63.0902061222020.14142@muncher.cs.uoguelph.ca>

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Hi,

Thank you for reply, but:
I'm afraid sync mount is not an option:
mount_nfs: -o sync: option not supported

Tried acregmax=3D0 already, and that made no difference unfortunately.
Application level O_DIRECT is not an option for us, so I'm wondering =20
what can be done at mount level?

thanks,
Joe

Id=E9zet (Rick Macklem <rmacklem@uoguelph.ca>):

>
>
> On Fri, 6 Feb 2009, Rick Macklem wrote:
>
> [stuff snipped]
>>
>> If the recent writes need to be visible on other clients (and not just th=
e
>> NFS server), you will also have to bypass the client side caching for
>> readers. This can be done by setting nfs_directio_enable to non-zero
>> using sysctl and opening the files with O_DIRECT. (I think setting
>> acregmax=3D0 as a mount option should achieve the same result, if you can=
't
>> add O_DIRECT to the apps.) Again, a big performance hit, but...
>>
> I know it's weird to reply to my own post, but I realized I should clarify
> that setting acregmax=3D0 will only achieve this approximately, based on
> the clock resolution used for the file's modify time. Setting acregmax=3D0
> should disable client side attribute caching, such that the client always
> does a Getattr against the server. Then, if the mtime attribute for the
> file has changed since the client cached data, it will be purged. As such,
> this only works when the mtime has changed and that will be based upon
> clock resolution (and if the mtime got saved on the server's disk, for the
> case where the server has crashed/rebooted).
>
> Have a good weekend, rick






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