Hi,
I could not understand why does RPC layer
underneath NFS client retransmit the request while
using NFS over TCP. TCP does reliable delivery of RPC,
ain't it? Is it because NFS server may drop the
requests/connection at its end?
Thanks in anticipation
Amey
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On Wed, Sep 10, 2003 at 09:04:44PM +0100, Amey Inamdar wrote:
> I could not understand why does RPC layer
> underneath NFS client retransmit the request while
> using NFS over TCP. TCP does reliable delivery of RPC,
> ain't it? Is it because NFS server may drop the
> requests/connection at its end?
In addition to trond's answer, note that when a TCP stream fails, you
have no idea how much information was lost. The acks and retransmits
allow the client to simply re-open the TCP connection, and no
transactions get lost.
-- greg
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On Wednesday September 10, [email protected] wrote:
> Hi,
> I could not understand why does RPC layer
> underneath NFS client retransmit the request while
> using NFS over TCP. TCP does reliable delivery of RPC,
> ain't it? Is it because NFS server may drop the
> requests/connection at its end?
Yes.
NeilBrown
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>>>>> " " == Amey Inamdar <[email protected]> writes:
> Is it because NFS server may drop the requests/connection at
> its end?
That is correct... Neither NFSv2 nor NFSv3 offer any guarantee that
the server won't drop requests if resources are scarce.
For NFSv4, there is a special error to indicate that the server has
run out of resources, and so retransmission should only be necessary
if/when the TCP connection is broken.
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