Re: PROBLEM: knfsd misses occasional writes

[Neil Brown]

On Wednesday May 15, [e-mail] wrote:
> 
> Hello everyone, 
> 
> When copying lots of small files from multiple NFS clients to a kNFSd
> filesystem (i.e. doing backup of a cluster), exported with `sync', I
> find that some few files (1 out of 1000) were silently truncated to zero
> size when checking locally with `ls' (the clients reported total
> success). With `asynch' instead, all files were correctly copied. 

How are you mounting the file systems on the clients?
The symptoms sound exactly like you are using "soft" mounts.  "soft"
is a very bad mount option.  Use "hard".

If you aren't using "soft", let me know and I will look harder.

NeilBrown

> 
> I have seen this behaviour in 2.4.17 (UP and SMP builds, UP hardware) as
> well as 2.4.18, when using the NFSv2 protocol. I have not tried 2.5.x
> and NFSv3 yet. The full /etc/exports line is:
> 
>    /opt/telorb 172.16.0.0/255.255.0.0(rw,sync,no_wdelay)
> 
> Removing `no_wdelay' makes no difference.
> 
> The clients are all 2.4.17, and the relevant .config lines (for both
> server and clients) are:
> 
>    CONFIG_NFS_FS=y
>    CONFIG_NFS_V3=y
>    CONFIG_ROOT_NFS=y
>    CONFIG_NFSD=y
>    CONFIG_NFSD_V3=y
>    CONFIG_SUNRPC=y
>    CONFIG_LOCKD=y
>    CONFIG_LOCKD_V4=y
> 
> Reading the source (fs/nfsd/*) seems to show that knfsd tries to do the
> right thing.
> 
> /Sverker Wiberg
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