Very Computer

by **Chris Kempste** » Sat, 20 Jun 1998 04:00:00

Does anyone know what SDU means?, the parameter can be used in the tnsnames
and listener.ora files and has a default value of 4Kb (to 32Kb). After some
prelim testing is can improve sql*net connectivity from client to server
from about 5 to 20%. I picked up the parameter from an old sql*net tuning
white paper done in early 96/97 but after searching all the sql*net manuals
can find nothing on it.

Any ideas?

by **saar** » Sat, 20 Jun 1998 04:00:00

> Does anyone know what SDU means?, the parameter can be used in the tnsnames
> and listener.ora files and has a default value of 4Kb (to 32Kb).

SDU is Session Data Unit
TDU is Transport Data Unit
(read on ISO 7 layers)

you must change on both client (tnsnames.ora) & server (listener.ora) otherwise
smaller value will be used.
syntax is:

client:
alias = (DESCRIPTION=
(SDU=4096)
(TDU=4096)
(ADDRESS= ... )
(CONNECT_DATA= (SID=test)))

server:
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SDU=4096)
(TDU=4096)
(SID_NAME = test)
(...rest of stuff..)

Quote:> After some
> prelim testing is can improve sql*net connectivity from client to server
> from about 5 to 20%.

Look at following two stats to indicate whether playing with these parameters
will help:

SQL*Net more data to client
SQL*Net more data from client

If they are clibming then set SDU TDU to higher values, this will prevent
SQL*Net
from breaking a packet into smaller ones. less packets faster response...most
of the time...

Saar.

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by **Dominic Lancaste** » Mon, 22 Jun 1998 04:00:00

> Does anyone know what SDU means?, the parameter can be used in the tnsnames

SendDataUnit perhaps - I've seen it before and depending on the typical
packet
size that the Server is sending back to the client may make it more
effective
if the average pktsize is greater than 4K to increase (as you have found
out).
It's a case of suck and see. The other usefull parameter goes into
protocol.ora
and is something like TCPNODELAY=ON, read up about the Nagle Algorithm
but essentially
if you have two large machines talking through high speed comms with
LARGE TCPIP Buffer
spaces, you pay a penalty if the buffer is not filled up to half way
with
data, ASSERT(fuzzymemory)(~200ms/pkt) ASSERT(OFF)

I know on AIX you need to request the patch from Oracle support to
enable the
feature (7.3.3 ???????)

Hope that helps

Dominic

Quote:> and listener.ora files and has a default value of 4Kb (to 32Kb). After some
> prelim testing is can improve sql*net connectivity from client to server
> from about 5 to 20%. I picked up the parameter from an old sql*net tuning
> white paper done in early 96/97 but after searching all the sql*net manuals
> can find nothing on it.

> Any ideas?

Very Computer

SDU setting - tnsnames, listener.ora

SDU setting - tnsnames, listener.ora

SDU setting - tnsnames, listener.ora

SDU setting - tnsnames, listener.ora