What strategies and practices are used, when running very intense and long calculations, to ensure that hardware isn't damaged?

Question

I have many large Fortran programs to run at work. I have access to several desktop computers and the Fortran code runs over takes several consecutive days. It's essentially running the same master module many times (lets say N times) with different parameters, something akin to Monte Carlo on steroids. In that sense the code is parallelizable, however I don't have access to a cluster.

With the scientific computing community, what practices and strategies are used to minimise hardware damaged from heat? The machines of course have their own cooling system (fans and heat sinks), but even so running intense calculations non stop for half a week cannot be healthy for the life of the machines? Though maybe I'm over-thinking this?

I'm not aware of any intrinsic functions in Fortran that can pause the code to give components a break? Current I've written a small module that keeps an eye on system clock, with a do while loop that "wastes time" in between consecutive runs of the master module in order to discharge heat. Is this an acceptable way of doing this? The processor is, after all, still running a while loop.

Another way would be to use a shell scripts or a python code to import Fortran? Alternatively are there any intrinsic routines in the compile (gfortran) that could achieve this? What are the standard, effective and accepted practices for dealing with this?

Edit: I should mention that all machines run on Linux, specifically Ubuntu 12.04.

Answer 1

For MS-DOS application I would consider the following:

• Reduce as much as possible I/O operations withHDD, that is, keep data in memory as much as you can, or keep data on a RamDisk.A RamDisk driver is available on Microsoft's website.

Let me know if you won't be able to find and I look at my CD archives

-Try to use Extended Memory by using aDPMI driver

DPMI - DOS Protected Mode Interface

-Set CPU affinity for a second CPU

• Boost a priority to High, butI wouldn't recommend toboost toReal-Time

Answer 2

I think you need a hardware solution here, not a software solution. You need to increase the rate of heat exchange in the computers (new fans, water cooling, etc) and in the room (turn the thermostat way down, get some fans running, etc).

To answer the post more directly, you can use the fortran SLEEP command to pause a computation for a given number of seconds. You could use some system calls in Fortran to set the argument on the fly. But I wouldn't recommend it - you might as well just run your simulations on fewer computers.

To keep the advantages of the multiple computers, you need better heat exchange.

Answer 3

As long as the hardware is adequately dissipating heat and components are not operating at or beyond their "safe" temperature limits, they * should be fine.

*Some video cards were known to run very hot; i.e. 65-105°C. Typically, electronic components have a maximum temperature rating of exactly this. Beyond it, reliability degrades very quickly. Even though the manufacturer made these cards this way, they ended up with a reputation for failing (i.e. older nVidia FX, Quadro series.)

*Ubuntu likely has a "Critical temperature reached" feature where the entire system will power off if it overheats, as explained here. Windows is "blissfully ignorant." :)

*Thermal stress (large, repeated temperature variations) may contribute to component failure of IC's, capacitors, and hard disks. Over three decades of computing has taught that adequate cooling and leaving the PC on 24/7 actually may save wear-and-tear in my experience. (A typical PC will cost around $200 USD/year in electricity, so it's more like a trade-off in terms of cost.)

*PC's must be cleaned twice a year (depending on airborne particulate constituency and concentration.) Compressed air is nice for removing dust. Dust traps heat and causes failures. Operate a shop-vac while "dusting" to prevent the dust from going everywhere. Wanna see a really dusty computer?

*The CPU should be "ok" with it's stock cooler. Check it's temperature at cold system boot-up, then again after running code for an hour or so. The fan is speed-controlled to limit temperature rise. CPU temperature rise shouldn't be much warmer than about 40°C and less would be better. But an aftermarket, better-performing CPU cooler never hurts, such as these. CPU's rarely fail unless there is a manufacturing flaw or they operate near or beyond their rated temperatures for too long, so as long as they stay cool, long calculations are fine. Typically, they stop functioning and/or reset the PC if too hot.

*Capacitors tend to fail very rapidly when overheated. It is a known issue that some cap vendors are "junk" and will fail prematurely, regardless of other factors. "Re-capping" is the art of fixing these components. For a full run-down on this topic, see badcaps.net. It used to be possible to re-cap a motherboard, but today's 12+ layer and ROHS (no lead) motherboards make it very difficult without specialty hot-air tools.