sdu, send/recv buffers, etc.
Date: Thu, 11 Feb 2016 14:50:57 -0400
Message-ID: <CACH2ED+_GWoLkPtXo=UoJHXP0NiKfeeErwS9Q5iHWTELUZpZ6w_at_mail.gmail.com>
Last week I looked on the 'net for recommendations on these. Clear as mud. Often the values people quote in the forums or on their blogs doesn't mention what network throughput they have, or even the operating system they're running on.
Same lack of precision on the multiple web pages mentioning Windows registry settings to tune tcp/ip on WAN networks: Almost none of them mention what version of Windows they are talking about or what throughput they have. I can't remember finding one that showed statistics before and after. I am a bit leery because pre-Y2K I tried using RAW partitions on Windows and discovered it made zero performance difference.
Oracle set SDU max size to 65535
On Ethernet though it's more useful to set it to 32120, right?
There is a blog page which tracks down some confusion in one of Oracle's
own tech note pages, which ended up being replicated on dozens of Oracle
DBAs' blog pages. SDU ought to be a multiple of the MSS, not the TDU.
MSS on Ethernet is 1460.
(ref. This DBA blog (5/6th of the way down)
http://khalidthedba.blogspot.ca/
)
The send and recv buffer sizes depend on the round trips, OakTable mentions
x1 but as of 10g I saw x3 being used. x Mbps throughput / 1000000 x round
trip ms / 1000 x 3 ? Hopefully your network doesn't have full-duplex
half-duplex mismatches.
Has anyone seen major improvements by tweaking these parameters for WAN
links?
We're serving Oracle Forms over WAN and some user sessions were seeing
disconnections.
After tweaking networking settings the disconnections seem to have stopped,
but performance hasn't improved all that much. At least... one user told
me he saw no performance improvement.
This thread shows some improvement, in that larger SDU sizing reduced the
amount of "more data to client". I used to see that as well but now it's
gone.
http://scn.sap.com/community/oracle/blog/2013/02/07/oracle-sqlnet-researching--setting-session-data-unit-sdu-size-and-how-it-can-go-wrong
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