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SDU, TDU, and MTU
Yesterday, I have spend some time experimenting with the
SDU parameter for optimizing a network connection with an
Oracle database. I was adviced to increase the value of
this parameter to 32768. But
somewhere I also read that the value of SDU should
not be higher than the
MDU.
Using ping, I discovered that the value for MTU for
the connection I am using is 1500 and that the effective
maximum data load is 1472 (that is 1500 minus the 28 bytes
needed for the IP/ICMP headers). Whenever you want to send
a data package larger than 1472 it is going to framented,
e.g. split in more than one package. I also found
this note by Steve Adams, which suggests that because some additional
headers that are used by the SQL*Net protocol, the value of
SDU should even be smaller than MTU. He arrives at the number
of 1450 bytes, where he calculates that the MTU is 1476, which
is four more than the value that I arrived at.
But when I searched Oracle, I found
this "Oracle Net best practices" PDF, which claims
that SDU and MTU are independent. The document does not
mention TDU at all. I guess that the above mentioned
remarks are based on out-dated facts.
I spend some time studying the following documents:
sqlnet.ora documentation,
tnsnames.ora documentation,
listener.ora documentation, and
Chapter 14: Optimizing Performance of the Database Net Services
Administrator's Guide. It is always a whole search to
find out how these kind of things work, and a simple
internet search does not always return the correct answers.
Playing Go
This evening, I went to the university to play Go. But before I arrived at the campus and also on
the campus, I saw many traffic wardens along the roads, because
of an important soccer match in Grolsh Veste. Before I went into the building, I asked
when one of the wardens when the match over, and he told me
that it was half past ten. I decided to leave for home before
that time. Taco arrived at the same time as I, and we decided
to play with a seven stone handicap for him. About half way
the game, Araldo arrived, and watched us playing. After the
117th move, I resigned. We replayed and analyzed
the game. Taco felt that I played less solid than normal. I
guess, I am playing more agressive. In a sense, I think this
is good, because I feel that often playing too passive. Although
I lost the game, I feel that I did learn something.
I left around a quarter past ten. From the cheering it was obvious
that FC Twente
was winning the games. When I arrived at home and the game was
over, I could even hear the cheering from our back garden. It
is 4,310 meter from our back garden to the center of the soccer
field. FC Twente won with 2-1 from Schalke 04. At home I reconstructed the game record of the
game I played against Taco. It went quite easy, also because it
only had 117 moves.
Going into the city
This morning, Li-Xia asked me if I could show her the
Bouwhuislaan where Andy goes because some weeks
ago she could not find it, and we also had to return something there. The
weather looked nice and we left around a quarter to two. First we went to some
shop to order some Curmaxell from Springfield. Next we biked to the
Bouwhuislaan and after returning the item, we biked to the Medialab in the
Tetem II building to have a look at the Nemo Observatorium by Lawrence Malstaf. First I went inside, and next Li-Xia gave
it a try. I took some pictures (the first). Finally, I went in again, and took some
pictures from the inside (part of one of the pictures). Next we went to the center of
the ciry and parked our bikes with bookshop De Slegte, but we first went to bookshop Broekhuis. We went to the third floor and had looked at the
kunstbBende exhibition of works by
seventeen employees of the bookshop. I found a pen drawing of a railroad
crossing quite interesting. Next we went to the second floor, where I selected
the Book by Book diary (picture)
from Bekking & Blitz Publishers.
Li-Xia felt a little sick and wanted to wait outside while I looked at
some books. After this we also visited De Slegte together. And we
also went to bookshop Kruimeltje,
which was the first time for her. We looked at some other shops and
arrived at quarter to five at Camel where we had an appointment at
five with Annabel for dinner. She promptly arrived and we ordered some
Donner Kebab and Falafel. Afterwards we went to a supermarket for some
shoppings.
Herpes Simpex connection
It seems that there are strong indications (see the article
Herpes simplex virus type 1 DNA is located within Alzheimer's disease
amyloid plaques, press release
Cold sore virus linked to Alzheimer's) that there is a connection between
the Herpes Simplex virus and Alzheimer's Disease.
An article by Simon Cooke gives some suggestions about
what you can do to stop the Herpes Simplex virus. I find it
interesting that he mentions Curcumin.
Cookies
Lately, Annabel has grown an
interest in baking cookies. Last Sunday, she bought some
utensils and also some decorative sweets. Today, I brought
some cookies
with me to the office that she made yesterday together
with Li-Xia.
Playing Go
This evening, I went to the university to play Go. I brought some cookies from Annabel with me. It was soon decided that Rudi would
play against Taco and me simulateously. Rudi and I agreed
on a handicap of eight stones for him. He played tengen,
that is exactly in the center of the board. Tengen means
center or origin of heaven in Japanese. I cannot recall, he
played this move, as his first move, while playing against
me. At first I did not worry about it, but soon I realized
its power. Before I got into the middle game, I had spend
more than twenty points to create a living group with two
points. Before counting, I took a picture of the board.
I finally lost with 30 against 9. We replayed our game and
analyzed it. At home I spend some time reconstructing
the game record.
Multi file fix
Sometimes, it happens that I have to fix some error
(usually a spelling error) in many files. Today, I
decided to write a
small program for doing this. The idea is that
you use grep with the -n switch and redirect the output
to a file. You open the file in an editor fix all
the errors and call multifilefix and pipe the file
into it, and if you want to really apply the changes
use the -sure switch (otherwise, it simply displays
what it would have changed).
The Way of Go
Today, I finished reading
The Way of Go
by Troy Anderson, which I started reading on November 27
when I bought it that same day at 12:45:53 from
bookshop "De Slegte"
for € 12. The book is about the
game of Go and it is not. The rules are only explained
in the appendix, and I have to admit, it is one of the best
introductions that I have seen so far. The books talks about
strategical principles applied to business and life, which
he derived from the game of Go, because it is a game in
which strategy plays such an important role. At some points
I found the book a little long-winded. I think that the
book could possibly be reduced to half of its size, if he
would have focused more on the great stories he has to
tell. In some chapters these stories are spread out over
the whole chapter. Nevertheless, it is a very interesting
book, because not many books talk about strategical thinking.
Two Women and Blue Mondays
Early today, I finished reading
the book Twee Vrouwen (Two Women) by
Harry Mulisch which I started reading yesterday. On
Christmas day, I got the book from my mother who again got
it for free from the library. I read the book for the
first time in February 1978. I was attracted to this book
after seeing the movie the movie Twice a Woman some months ago. I really found this
to be a very beautiful, truely literary work.
This morning, I finished reading the book Blauwe Maandagen
(Blue Mondays) by Arnon Grunberg, which I started reading on December 14
after buying the book on November 2.
This book started much like his later book Figuranten.
The third part of the book, called Dancing like an Egyptian,
made an impression on me, because it was about his father who
had become demented due to cerebral haemorrhage or infarction.
But after that, in the last two parts of the book, I felt that
the book was going down-hill, and I only finished it because I
already had come that far reading it, and I was hoping that it
would end in some positive turn. It was about drinking alcohol
and escort girls. If this book is really that autobiographic as
it seems to be, than Grunberg went through a rather dark periode
in his life.
Resveratrol Extra Forte
Today, I bought a bottle of Resveratrol Extra Forte from Reformhuis Twente, which we had ordered yesterday.
Resveratrol is a component from red wine, which seems
to be responsable for the positive health effects.
It is also said to work against Herpes Simplex, een virus
that has been linked with with
Alzheimer's Disease.
Last week we also added L-Lysine to the supplements that
Li-Xia takes every day.
This months interesting links
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Tuesday, December 9, 2008
Wednesday, December 10, 2008