Thu, 20 Mar 2008
Mainframes
Today's presentation of industrial partners of our Faculty was about mainframes. I have really looked forward to see it, because from time I hear how mainframes are superior to the ordinary computers, etc, so I wondered whether and why it was true.
It was a total waste of time. Not only the speakers were not much experienced with presenting, but also the talk was almost information-free. For example, they described a typical set of components in a mainframe, which was a block diagram with parts which (as I understand it) have their equivalents in common PCs. They however did not tell us whether or how they are different.
They also discussed which programming languages can be used for programming mainframes. Instead of showing a single slide with the list of languages, and maybe explicitly mentioning one or two most uncommon ones, they spent several minutes saying things like "We also support C++, which is the language deveoped in 199x, and it is object-oriented. We can use Java, which is also object-oriented, and on top of that it is interpreted.". And so on.
The presentation also included plain lies, such as saying that the newest mainframe (released few months ago) with 1.5 TB of RAM and 64 quad-core CPUs is roughly equivalent to 1500 PCs: when compared to my new workstation I highly doubt that (if I compare the memory, I get the factor of 187.5, and for the number of cores I get 128; and I think the mainframe cores as well as the memory will be slower because of the HA/RAS features and looser coupling in the bigger system).
Also the good old ignorance was there: they said that most of the Internet is running on the mainframes (whatever that means :-), and something along the lines of "I have tried to search what hardware Google uses - I didn't find it out but I bet they run on IBM mainframes".
So the whole question whether mainframes are interesing and why should I use them remained unanswered. I really hope the next week it will be better - Dan Walsh of Red Hat will be presenting SELinux (Thursday 27th 14:00, FI MU, room D3 - you are invited to come).
UPDATE 2008/03/20: Dan Walsh's talk
As you can read in comments (thanks!), apparently Dan Walsh's talk on SELinux
will be on Tuesday, April 1st, 12:00 instead.
1 replies for this story:
Miroslav Suchý wrote: Walsh presentation has been shifted
Walsh presentation st FI MU has been shifted to 1.April at 12:00.
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Tue, 18 Mar 2008
New Workstation
On Friday, my new workstation arrived. My previous workstation was 4+ years old Athlon64 FX-51, one of the first three AMD64 computers here at the faculty (the other two were Odysseus, and our secondary router, which had a mainboard failure a month or so ago). The new computer is Athlon64 X2 (finally a SMP on my desk!) with ASUS M2R32-MVP mainboard. There are some interesting features of the new computer:
- The BIOS can be upgraded from the BIOS itself, no need to create DOS boot floppy anymore - just put the ROM image to the USB flash stick and you are done!
- The BIOS is localized (I have tried to switch it to Japanese for the coolness factor :-).
- My first desktop computer without a floppy drive :-), I have a neat card reader instead.
- The memory controller can interleave the banks not only line-by-line, but also based on XOR of some higher order address bits (something like 10 to 14, IIRC), which allows multiple threads to use the independent memory channels.
- Huge (12 cm?) chassis fans, so the system is more quiet than the previous one, while providing good cooling to the disks.
- The case with the whole front side perforated for better cooling.
- Hardware virtualization support: I will finally be able to test other systems like some *BSDs and OpenSolaris.
There are obviously some drawbacks too:
- I had problems with the SATA controller in AHCI mode, solved fortunately by a BIOS upgrade.
- The graphics card (ATI X1650PRO) does not work in Zaphod mode (i.e. two separate screens, opposite to Xinerama/MergedFB/XRandR, which work). I have temporarily solved this by using an older card (X300 something).
1 replies for this story:
Yenya wrote: Grammar fixes
Fixed grammar errors (thanks to Michal Fikera!)
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Tue, 11 Mar 2008
What is Jabok?
One of the Iva's favourite pastimes is that she thinks up a random word and asks me whether it does mean anything. Yesterday she asked: "What is JABOK?"
Well, I happen to know what Jabok is, so I said Jabok is a school. She thought up another one and asked: "Is it also a school?" I said I don't know. "Why?" "I don't have a big enough head to hold the names of all schools in the world there". Her answer was really stunning:
"Does an elephant know all those names?"
4 replies for this story:
Vasek Stodulka wrote:
I am looking forward to play such games with Vendula (now she is one and half month old). She recently learned how to smile and now she is trying to take control over her voice - today at morning she was "talking" to me and smiling for maybe 15 minutes. It is beginning to be fun with her. BTW: very cute picture.
errhm..hmm..yesihavesome wrote: sooo funny
Pánové, nic proti Vendulce nebo Ivě, ale proč se dva inteligentní lidé vybavují lámanou (protože nikoliv nativní) angličtinou, když oba jistě umí dobře česky? Nejste na meetingu, takže není třeba dělat vlny..
Yenya wrote: English
Well, one of the purposes of this blog is to improve my English. I use my English for reading mostly, so I need to practice it also by actively writing something. If you are aware of any grammar or spelling mistakes in my blog, you are welcome to point them out. On the other hand, comments are welcome even in Czech or Slovak (or maybe Japanese?).
errhm..hmm..yesihavesome wrote:
Your English is very good, probably better than mine. The only thing that (IMHO) cries "I am not a native speaker" is that it's slightly too verbose. But who cares..
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Mon, 10 Mar 2008
JLPT-4 Done!
As I wrote before, last December I have taken a Japanese Language Proficiency Test (4-kyu) exam. Today I've got the results: I have fortunately passed with 348 points out of 400 (i.e. 87 %), which is not so bad.
Now let's see whether I can manage to pass the 3-kyu this December. It means about 200 more Kanji and 700 more words learned, not counting things like grammar. So far I have found the following site with JLPT 3 resources. Unlike other sites, they at least have the Kanji and vocabulary in plain text form (and not Kanji images), so it is usable for importing into the learning software, etc.
Also I have found a nice archive of images of Kanji stroke order (available as animated GIFs or still PNGs with all phases in one row), and it even has a relatively free license, so it is usable in the learning software without tricks like deep linking.
1 replies for this story:
Peter Kruty wrote: Congratulations!
Congratulations Yenya and good luck with the 3rd kyu.
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Wed, 05 Mar 2008
Server-grade Disks
For a long time I have been wondering how the so called "server-grade" hard disk drives differ from the consumer-grade hardware. I tend to think the difference is precisely zero, provided that the other specs (RPM and capacity) are the same.
There is a well-known paper from Google researchers (PDF warning), which supports my opinion. For example, in our IBM FAStT-600 array with 28 250 GB SATA drives we have replaced about half of the drives, and from the consumer-grade 250 GB P-ATA drives in our other servers the failure rate is about the same.
Last week we have replaced our backup server by a new hardware with newer and bigger drives, and I have looked at the old server whether some of the drives
would still be usable: I have found two 250 GB P-ATA drives which both had
zero errors logged in the SMART log, and both had over 36,000 hours of usage
(4 years and 1.5 month)! I remember they were previously installed in
Odysseus (aka ftp.linux.cz), where they were almost continuously busy for at least a year and half.
So the next time some salesdroid would try to persuade you about the different firmware and higher manufacturing standards of the "server-grade" drives, do not buy the snake oil!
1 replies for this story:
Spes wrote: RAID edition drives
BTW when I was buying some drives to fadmin.fi.muni.cz, I was interested in what is the difference between ordinary and RAID edition drivers by WD. I got answer that the RAID drives try to obfuscate SMART log as long as a (more) serious problem occurs.
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Tue, 04 Mar 2008
Presentation Charts
The "most funny image of the day" award goes to this one:
Seen at Slashdot, the source URL is http://www.presentationzen.com/presentationzen/images/2007/03/16/pacman.jpg.
1 replies for this story:
Vasek Stodulka wrote:
LOL, good one. I'll use this in some presentation.
Reply to this story:
Mon, 03 Mar 2008
Fighting With Beamer
A while ago I wrote about typesetting presentation slides in Beamer. Now I have decided to rewrite the slides for my UNIX courses in Beamer, but it brings many problems - I will write about two of them:
The first problem is with typesetting the C source code (quite frequent task
for the UNIX course): I cannot use the
[fragile] option to the frame environment,
because it writes the text to the file and rereads it again, messing up
the character encoding during the process (I use UTF-8 input encoding).
I cannot use the semiverbatim environment, because the most
tricky part - the indentation of the source code - is not preserved.
The second problem is with graphs and diagrams: I want them to have the same font as the surrounding text (both in typeface and size). So the file format should be something like LaTeX (for texts) + something for rectangles, lines, arrows, and other vector graphics. I have tried about all the formats XFig supports, but none of them work with PDFLaTeX, UTF-8 encoding, and meets the above requirements.
So, my dear lazyweb, how would you solve the above two problems (other than using OOImpress or something similar)?
4 replies for this story:
mf wrote:
I really don't know about the first one. I'm trying to stay away from utf8 as much as possible. As for the second one, pdflatex and vector graphics gives you only one option. You should create a separate pdf file with your graphs and diagrams and then embed it in your presentation using graphicx package. It shouldn't be too hard to make text with the same properties, but I really don't feel like playing with it right now.
Kirk wrote: second one: asymptote?
http://asymptote.sourceforge.net/
Yenya wrote: Re: asymptote
I have tried asymptote (thanks!), but I think xasy is too simplistic for my needs. And I don't need a non-interactive tool like the asymptote language (or MetaPost).
luispedro wrote:
How about \newcommand{\ind}{\hspace*{1.5em}} and then indent manually \begin{semiverbatim} for X in list: \ind X.process() ...