Re: Urgent help needed on an NFS question, please help!!!

From: Trond Myklebust
Date: Thu Aug 10 2006 - 20:42:52 EST

On Thu, 2006-08-10 at 18:25 -0400, Xin Zhao wrote:
> The inter-VM inode helps reduce communication cost used to retrieve
> file attributes in a VM environment. In a network environment, it is
> possible for a client to direct see the inode caches of the server.
> But in the virtual server environment, where both client and server
> running on the same physical host, this would be possible.
> If clients have read-only access to server's inode cache, they can
> directly retrieve file attributes without incurring expensive
> getattr() rpc call. Of couse the delegation is able to allow a client
> to trust local cached file attributes without worry about server
> change. But this only works when file is not shared by multiple
> clients. Right? Does NFS4 has some other mechanisms that can further
> improve performance on metadata access?

Not metadata access, no. That would require some seriously messy locking
It improves performance by allowing a client to access the block device
directly for data reads and writes if it has the capability of doing so.


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