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Ask Slashdot: Linux Login and Resource Management In a Computer Lab?

Fotis Georgatos Re:Just deal with problem users individually. (88 comments)


I've been managing systems with hundreds of well-meaning and not-so- scientists, for years.
Generally, I subscribe to the school of thought that putting too many fences does more damage than good.

I know for myself, that I *can* create trouble in a zillion of ways on a system, that fencing against it is almost pointless:
* fork bombs
* malloc bombs
* /tmp overuse
* /dev/shm overuse
* deliver daemonized processes in the background
The first two you may handle a bit with the PAM limit techniques described by a fellow poster, but not without limiting the capabilities of the system (ie. you take out useful features, to enforce some policy). The rest you can attempt to handle with some other clumsy fencing techniques, but again not without side-effects.

In short, do not overengineer, yet be totally reactive: let the rules be relaxed in the beginning, monitor tightly, react quickly and be sure to have often your users at the other end of the phoneline/email justifying their tasks' activity. You'd be surprised how much you'll discover by doing that and policies will be far more justified.

> One thing that shouldn't be underestimated is the ability of a user (especially a young user) with *lots* of free time on his/her hands to figure out ways to game the system...

Also this!
Young users with lots of free time will give you a headache, one way or another. But you can often stop them by just blinking an eye.

11 hours ago

Ask Slashdot: Switching From SAS To Python Or R For Data Analysis and Modeling?

Fotis Georgatos Both Python & R great, yet do check under the (143 comments)

To begin with, I'm a Pythonista for much of the time. Even so, I can see how you will probably land in the world of R; here is why:

  • * R comes with reasonable facilities for statistical processing and, on top of that, has important extensions that allow for remarkable features. Example: Setup R language, with snowfall->snow->Rmpi extensions. The result of this would be *fault-tolerant* *scalable* code, within relatively simple codebase. It cannot be overemphasized how much functionality you get out of the box in such setup, with basically zero code changes (in R).
  • * Python is great when it comes to integration with other languages/codebases. It could well be the best scripting language since... the invention of bread. As another poster mentioned, it can also interface with R via Rpy, so it's not at all a black-or-white decision.

In short, both are first-class tools for scientific computing and you should compare and choose them on technical merits basis.

about three weeks ago

Why Scientists Are Still Using FORTRAN in 2014

Fotis Georgatos Memory management (634 comments)

The biggest reason of interest is that it helps non-computer-science scientists write up computational codes, neither having to devote excessive amount of time in memory management, nor deviate from the classic imperative programming model. And, it is also important for a purely non-technical reason: a generation of domain experts in engineering and scientific domains where trained in FORTRAN codes.

As managers of High Performance Computing platforms, we generally take an a-religious approach and deliver to the users all possible permutations of language types that a given community may need. The following is a very common setup, containing both GNU & Intel compilers:

btw. I'm not defending Fortran in any kind of way; ask any Fortran-fun, in which language his compilers are written in ... there is a reason :)

about 2 months ago

Ask Slashdot: Beginner To Intermediate Programming Projects?

Fotis Georgatos EasyBuild, it is in Python (172 comments)

IFF you have even done wget/tar xvf/patch/make/make install - and wondered,
if this process could be ever improved and make sense, you have found your project!

EasyBuild allows you to tame scientific software of the following type:
* Download and build GROMACS over FFTW/3.3, applying patches X,Y,Z, using CUDA for speed.

Here is your initial reference:
And here is the juice:
The code lives across 3 repos on github, I am sure you will find your way.

about 2 months ago

Ask Slashdot: System Administrator Vs Change Advisory Board

Fotis Georgatos Maintenance Windows (294 comments)

Probably all you are missing over there are scheduled maintenance windows.

You give them a list once per month about what is about to change, get a confirmation, proceed with them available on standby for fixes on the spot or, rollback.

Try to think the big picture: how would you maintain the systems, if they were life-supporting medical equipment? Why not give same quality of service?!

about 3 months ago

Mathematicians Use Mossberg 500 Pump-Action Shotgun To Calculate Pi

Fotis Georgatos Swap gun 4 cheaper more traditional geometry bits? (311 comments)

OK, the rope won't do as much for accuracy as actually working out the math a bit, but nevertheless it WILL be better and more guaranteed result than a shotgun.

Also, if you can curry a shotgun for the post-apocalyptic world, you can as well carry a clay tablet with "355/113" written on it and save on the bullets for the moments that you will be in higher need... (having a monopoly on circular constructions might make you a highly sought target :-P )

about 3 months ago

Ask Slashdot: What Software Can You Not Live Without?

Fotis Georgatos Re:GCC etc. (531 comments)

the longer version of what you started above is here: (different people need different subsets, but the total is a safe bet)

about 5 months ago

MtGox Sets Up Call Center For Worried Bitcoiners

Fotis Georgatos after all... (240 comments)

...setting up a phone consolation center is so much cheaper than meeting all those expectations about monies!

about 5 months ago

Plan 9 From Bell Labs Operating System Now Available Under GPLv2

Fotis Georgatos Re:been there (223 comments)

Add AIX into the mix of tried things; OO-DB at the heart of the OS... OMG!

about 5 months ago

Majority of Young American Adults Think Astrology Is a Science

Fotis Georgatos come on... (625 comments)

...they just meant "short off scientific"!!!

about 5 months ago

Ask Slashdot: Why Are We Still Writing Text-Based Code?

Fotis Georgatos Try this at home... (876 comments)

...attempt to provide visual alternatives to this kind of discussion on IPv6/IPv4 regex constructs: Human brain seems to work well with information in text format, despite complexity.

about 5 months ago

Ask Slashdot: What Online News Is Worth Paying For?

Fotis Georgatos oracle... (361 comments)

...machines' news!

about 6 months ago

In Greece, 10 Months In Prison For "Blasphemous" Facebook Page

Fotis Georgatos Re:Since i am a Greek... (324 comments)

The other Greek fellows that wrote around this article, I'd say that they portray well the different standing of opinions of the greek population at large, and even hint at the cause-effects of this "legal accident".
Most points are valid as opinions but I'd rather emphasize a couple points for clarity:

> In school is surely optional to pray and to attend the one hour per week religion class.

I'd differ in that: at the time I was in high school, the courses about religion WERE compulsory to attend and formed part of the final grade. So, it is a form of coercion. To be fair, most teachers had enough intellect to let things go by without mishaps.

> That "hold of the church over the state" i can not see it - i don't claim that you are lying but you exaggerate the situation.

Hm, we all wish it was the case: Few years ago my father made the claim in a related family debate,
that I am a citizen of a theocratic state. Of course, I gasped at the notion and refuted.

How wrong I was! the first line of the modern greek Constitution starts with: "In the Name of ... Trinity" ! eh!!!
The only think that consoles me is, that our occidental neighbor, Italy, needs to make even more steps for state-religion separation :)

about 6 months ago

Ask Slashdot: What's the Most Often-Run Piece of Code -- Ever?

Fotis Georgatos MPI calls: MPI_Send/MPI_Recv and co (533 comments)

OK, I think there is a fair proposition about this question.

First, let's agree on some observations:

  • * The per-clock throughput of CPUs has been on an exponential increase curve, per last decades, ie. last 20-30 years matter a lot
  • * The proliferation of silicon compute devices has been on the increase for decades, ie last 10-20 years matter a lot (from the very small to the very big)
  • * The duty cycle of most silicon devices is not 100%; there are two notable exceptions: infrastructure (embedded) systems and supercomputers
  • * Parallel computation implies fast interconnects for quick message passing; for some initial info, ref.
  • * Despite regular interconnect technology upgrades, MPI has been the agreed standard for message passing since the early 90s

ref. ->Statistics for more details; so, here we talk about big machines, of high duty cycle, of using mostly a uniform API for synchronization.

Given Weather, Climate & Computational Fluid Dynamics codes (and some more), the temporal density of such calls is pretty good.

Concluding, MPI should be the most common *API* being called nowadays per unit of time;
there is still room for challenging this though: MPI Send/Recv calls have a few variants plus,
MPI stack implementors may have fragmented the codebase, to declare a clear winner...

about 6 months ago

Why Do Projects Continue To Support Old Python Releases?

Fotis Georgatos Re:People don't upgrade (432 comments)

But, why aim for the least, when you *can* do the most? Environment-modules allow you to install multiple versions of software side-by-side, including multiple versions of Python. Furthermore, it is next to trivial to install few 2.x and 3.x versions by using EasyBuild, see for examples at: EasyBuild itself is written in Python and will run in any Python 2.x for x>=4. Last but not least, EasyBuild may prove to be the more sane way to install Python packages in a cross-platform way; anyone here having a better *cross-platform* offer?

about 6 months ago

Ask Slashdot: How Would You Stop a Debt Collection Scam From Targeting You?

Fotis Georgatos reply (497 comments)

by not replying, you do them a favor: you give them all the information they need to retry (noop => retry).

Try to put something like an answering machine, a hayes-modem with AT commands, Asterisk, whatever it takes to make sure you increase THEIR cost (the cost maybe monetary if they have no fixed landline costs or, other like human time, when they are on flat-fee) Likely, there will no shortage of such scams in the future, so you will get to re-use your equipment and effort.

Make sure you engage them otherwise, if everybody strays away from this, they have more chances to continue the scam.

btw. the Google Voice suggested by others is the right course/direction of action, if you have live business phone traffic coming in; otherwise, you risk your clients. (and if it is such the case, $20 is a no-brainer to better serve your customers)

about 8 months ago

Ask Slashdot: Cheap Second Calculators For Tests?

Fotis Georgatos HP-10s (328 comments)

At 11$, it should fit the bill; made for scientists and engineers, should pass its own exams with 240 functions. The manual is here: Why recommend it? I own it and it does the job, if the problem is really for a calculator :)

about 8 months ago



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