2009-04-20 09:57:30

by howard chen

Subject: [NFS] Will NFS client use write-back caching?

Hello,

My client is running ext3, which default has 5 seconds of write-back
caching, e.g.

cat /proc/sys/vm/dirty_writeback_centisecs
499

Now, if this client connect to a NFS (v3), and write data to the NFS,
will write-back caching used?

Or it will fsync() after every write ?

Thanks.

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2009-04-20 12:57:25

by Trond Myklebust

Subject: Re: [NFS] Will NFS client use write-back caching?

On Mon, 2009-04-20 at 17:56 +0800, howard chen wrote:
> Hello,
>
> My client is running ext3, which default has 5 seconds of write-back
> caching, e.g.
>
> cat /proc/sys/vm/dirty_writeback_centisecs
> 499
>
> Now, if this client connect to a NFS (v3), and write data to the NFS,
> will write-back caching used?

Yes. However it will always flush out data on close() in order to ensure
that other clients see the data (see
http://nfs.sourceforge.net/#faq_a8 ).

Trond


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2009-04-20 18:08:05

by Muntz, Daniel

Subject: Re: [NFS] Will NFS client use write-back caching?

NFS will do asynchronous writes by default, i.e., write-back caching.

-Dan

> -----Original Message-----
> From: howard chen [mailto:[email protected]]
> Sent: Monday, April 20, 2009 2:56 AM
> To: [email protected]
> Subject: [NFS] Will NFS client use write-back caching?
>
> Hello,
>
> My client is running ext3, which default has 5 seconds of
> write-back caching, e.g.
>
> cat /proc/sys/vm/dirty_writeback_centisecs
> 499
>
> Now, if this client connect to a NFS (v3), and write data to
> the NFS, will write-back caching used?
>
> Or it will fsync() after every write ?
>
> Thanks.
>
> --------------------------------------------------------------
> ----------------
> Stay on top of everything new and different, both inside and
> around Java (TM) technology - register by April 22, and save
> $200 on the JavaOne (SM) conference, June 2-5, 2009, San Francisco.
> 300 plus technical and hands-on sessions. Register today.
> Use priority code J9JMT32. http://p.sf.net/sfu/p
> _______________________________________________
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> https://lists.sourceforge.net/lists/listinfo/nfs
> _______________________________________________
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