CIFS read-ahead

Nicholas M. Kirsch nkirsch at isilon.com
Thu Jul 10 16:42:27 GMT 2003


>    I have done some work in this area, primarily to deal
> with filesystems which want quite large, aligned reads.
> Notably RAID disk arrays!
>    Can you describe your application to us? The cache read
> code **might** address your problem.

I have a very large (several terabyte) filesystem and I want good
single-stream read performance from it. The applications which do this are
many, including media streaming and simple file access in a single-stream
linear fashion.

I am working on a NAS appliance, which uses Samba 3.0 to provide CIFS
access to its content. Will your cache read code instruct the client to
read-ahead? What appears to happen is the CIFS client sends a read
request, and waits for the answer before sending another. In this
scenario, throughput will be limited by latency. It appears as if NFS gets
around this by sending multiple read requests at a single time.

I am not sure whether CIFS supports such things, just hoping.

Nick



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