Re: z/OS DFS SMB Performance

On Thu, 30 Mar 2006 20:29:15 -0500, John S. Giltner, Jr.
<giltjr@xxxxxxxxxxxxx> wrote:

From my experience SMB on any platform is slow. Think about it, a 200K
file loading in 5-9 seconds in the office. That is a transfer rate of
somewhere between 20 to 40 K a second. Now add the overhead of a VPN
and the latency and through put of something that is most likely much
less than the network between your PC and the mainframe at your work.

What is the slowest network connection in your office?
What is the speed of the network that your VPN is transversing?

What do you mean pulling it directly? FTP? FTP is much more efficient
that SMB.

SMB is real chatty. IIRC it does one ACK for every two data packets and
the ACK is not sent until the data packets are received. This is on top
of the TCP level ACK's.


I had a presentation by cisco people about their VPN accelerator ,their AVS
( appl velocity system) their WAFS ( wan accelerator for file system) and
WAE ( wan accelerator engine) ,
Obviously WAFS has been invented for the exact problem you are facing .
The chat to open a document with word or excell over a network .
The number they showed me was like 1000 exchanges to open and close a file
and they were dividing this by 8 or 10 , by letting only the security
portion of the handshaking flow ( enqueue etc .. ) and by simulating a big
part of this handshaking on both ends to reduce the chatyness , and trying
to let flow the data only .
The improvement is just tremendous .
try to find out on google how this WAFS , WAE and cisco accelerator work
and it will give you some good insight in what John is describing exactly .
Bruno
Bruno(dot)sugliani(at)groupemornay(dot)asso(dot)fr

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