delayed ack for ftp

[Wim Van den Wyngaert]

To get better Sybase performance, we disabled delayed ack on tcpip.

Now I found that FTP sessions ack almost all packets that arrive, which is overhead.

Is there a way to get delayed ack back only for ftp ?

I know there is a logical tcpip$ftp_setnodelay but that's one for getting nodelay and I want delay (btw : didn't find any doc on it).

[Willem Grooters]

I'm not sure this is possible and you will propably already looked into it: Can you disable ACK on a per-process basis? If so, do it the other way round. Just for the programs using Sybase, disable ACK, and leave teh standard as it is. It might be something to be programmed into your images, or defined (at the receiving side) in the service definition.

Agreed on the documentation: that, and help, on TCPIP is typically Unix-like: impractical if existing.

Willem

[Ian Miller.]

What about
TCPIP SET SERVICE FTP/PROTOCOL_OP=TCP=DELAY
and shutdown/startup the ftp service

[Wim Van den Wyngaert]

Ian,

Very good. I didn't see that option.

But I tried it and still got FTP not working in stream mode. Almost every packet received is acked immediately.

Wim

[Wim Van den Wyngaert]

And the option is only shown in show service ftp /perm, not in the volatile version.

Wim

[Martin Vorlaender]

On a related topic:

>>>
Can you disable ACK on a per-process basis?
<<<

Normally, you can *only* disable ACK on a socket basis: it's a socket option.

That's why I've been trying for years to get Process to implement it in TCPware/MultiNet the way UCX does it - it's just plain useful to disable it for the whole stack ;-)

cu,
Martin

[Wim Van den Wyngaert]

Martin,

As I understand it, the program behind the service must read the service parameters and implement them.

I have the impression that FTP is not using
the tcp option.

Wim

[Wim Van den Wyngaert]

Could it be that set protocol /nodelay
sets the option stronger than the service ?

When I do show prot tcp, I don't see ANY delayed acks being sent (based upon (xxx delayed).

Wim

[Wim Van den Wyngaert]

Btw : does anyone know a way to disable delayed ack for Sybase (servers) but different from disabling it on tcp level ?

Wim

[Michael Yu_3]

Hi Wim,

Perhaps we can toggle the tcp parameter tcpnodelack before and after the startup of sybase servers.

$ sysconfig -r inet tcpnodelack=1
$ startup sybase servers
$ sysconfig -r inet tcpnodelack=0

Thanks and regards.

Michael

[Wim Van den Wyngaert]

Michael,

Yes but then during a few seconds (multiplied by 5 servers), everything that is started gets nodelay.

And this requires changes in startup. Difficult to get over here.

Wim

[Michael Yu_3]

Hi Wim,

Perhaps you can put the following line inside the site specific startup for FTP and FTP_CLIENT.

$ sysconfig -r inet tcpnodelack=0

The files are SYS$STARTUP:TCPIP$FTP_SYSTARTUP.COM
and SYS$STARTUP:TCPIP$FTP_CLIENT_SYSTARTUP.COM.

Make sure that the sybase servers are started before FTP_CLIENT.

Thanks and regards.

Michael