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Re: high load, no bottleneck



On Thu, 26 Sep 2013, Emmanuel Dreyfus wrote:

Emmanuel Dreyfus <manu%netbsd.org@localhost> wrote:

     async   Assume that unstable write requests have actually been committed
             to stable storage on the server, and thus will not require
             resending in the event that the server crashes.  Use of this
             option may improve performance but only at the risk of data loss
             if the server crashes.  Note: this mount option will only be hon-
             ored if the nfs.client.allow_async option in nfs.conf(5) is also
             enabled.

I tried moving a client NFS mount to async. The result is that the
server never sees a filesync again from that client.

What are the consequences? I understand that if I use -o log
server-side, I will still benefit regular flushes. I will loose the
guarantee that client fsync(2) push data to stable storage, but I will
not have corrupted files on server crash. Is that right?

As I understand things, -o log (wapbl) doesn't guarantee file content, only fs metadata.


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