We have had trouble in the past with TCP. The failover of cluster pairs would hang our Solaris equipment, because they could not pick up the session with the partner. Haven't tested other OSs because only Solaris would mount with default TCP. Haven't tested recently either.
It sounds like the real problem is just that the server is getting overloaded and drops packets requiring retransmission and that overhead is reduced by the retransmission for only 8K blocks instead of retransmission of 32K blocks.
On the flow control; why back off from full flow control when the problem seems to be that flow control is needed?
At 5:57 PM +0100 2/22/02, Michael van Elst wrote:
On Fri, Feb 22, 2002 at 08:24:12AM -0800, Jim Harm wrote:
I have heard this from NetApp technicians and on this list, but The only thing I found on the NetApp web page search was a reference to a switch that would overflow the buffer when translating from gigabit ethernet to fast ethernet.
It also happens with just gigabit ethernet. There is on option for GigE flow-control, which helped us and two Catalyst 6509s somewhat. But since that's only point-to-point and not end-to-end flow control, you still get overflows if traffic passes multiple switches.
Someone please, point me to the bug description. We have seen the improvement, but we run GigE from client to server. None of the switches show errors or severe packet loss.
It is sufficient that packets get delayed randomly.
The server shows packet loss, but how is that decreased by smaller read and write sizes on clients?
If you send multiple packets in a row, the server may not have enough CPU time to process each packet. Smaller read and write sizes introduce artificial gaps which are often large enough to allow for processing.
Our switch software is supposed to be up to date. We see the problem alot and run UDP strictly, so,
What about TCP ? In our experience, the end-to-end flow control that you buy with TCP helps a lot.
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