Re: Oracle Data Guard

Can you clarify a couple of points for me.

The SDU (session data unit) is presumably the packet size that the Oracle client and server want to pass back and forth - which is presumably the maximum size the one synchronous dialogue unit will be.

The TDU (transport data unit) is presumably the predicted size of the transport maximum unit of data transfer (MTU).

1. Why does Oracle need to know anything about the underlying transport mechanism ?
2. If I set the SDU to the largest legal value (possibly 32K, perhaps 64K) the server task switch will occur after building and sending that packet - is there any good reason why I shouldn't do that. After all, if the transport simply accepts the 64K packet and gets it to the other end of the wire (not yet to the client session, just to the receiving transport layer) as rapidly as possible does it matter to Oracle whether the transport is using 1.5K or 8K packets. The fact that the transport layer doesn't have to work its packet synchronously means that some overheads have disappeared as far as Oracle is concerned.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, December 10, 2003 3:44 PM

> Hi, Guang,
>
> Look up SDU and TDU in Oracle documentation Network configuration. You set
them
> in tnsnames.ora and listener.ora, not sqlnet.ora. protocol.ora allows you
to
> modify some procotol-specific parameters. In addition, in your client
> application, you can choose a sensible array fetch size, such as arraysize
in
> sqlplus (in fact, sqlplus arraysize changes more than just network data
chunk
> size). You can't magically increase the network transfer rate by lowering
> network latency. But you can indirectly increase the rate by other means,
such
> as buffering slightly more data in one chunk.
>
> Yong Huang
>

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