[RC5] wear

Attila Csipa bear at prometheus.org.yu
Thu Jan 27 01:39:36 EST 2000


> I think it is an accepted fact that a hdd could be run to death if it were
> at full spin 24/7, no?

 Yes, but not in a year. I run a BBS system which has some disks running
for several years now (knock, knock), has been cracking RC5 keys for the
last two years (if it's already on, sitting idle...). THO if someone
would ask what component would die first, I'd say CPU-fan or HDD...

> (Afterall, hdds are spec-ed with MTFBs)

 Yes, but if calculate MTBF for disks you _will_ get some strange
results (most of the drives comes with about 250.000 hours MTBF which is
almost 30 years of 24/7 work). OTOH, you _should_ take into account that
laptop/notebook computers generally have less efficient cooling than
most desktop computers, which in turn can, _in some cases_, shorten
component life. OTOH, the interesting part is that one would expect that
the error should be in the mechanical part of the disk (friction and all
that), but if you cannot detect the disk in the BIOS, the error is more
likely in the electronic part of disk (though it could be that this part
detects the mechanical error and refuses to report itself to the BIOS if
it finds errors).

> What other components can be worn to death from running dnet?
> I've always believed the CPU to be immortal since it has no moving parts.
> True? Provided cooling is stable, which brings us to the cooling fans...
> these tend to clog with dust.. Anything else?

Hm, there are some issues if the CPU is overclocked, but I guess that's
not the case on your machines...

> What can I do to make sure the hdd spins down to powersaving (and
> low-wearing mode), when the computer is left alone to crunch rc5?
> Could we have user-definable disk-access frequency in the client?

You can do several things. Run dnet clients off of a ram disk, or set
the option 'use RAM only' (or something similar). Another, very popular
(at least around here) is to work on a floppy. The disk will spin down,
the data will not be lost if power goes down or the machine reboots,
although you should be careful not to use 10 year old floppy disks :)
Summa summarum - running a dnet client 24/7 cannot directly kill off
your machine or any of it's parts - but it can speed up some unwanted
physical processes, just as any other program (or even simply not
turning off the machine) would, if used in a similar manner. This is of
course my personal opinion, others (dnet staff, etc) may or may not
agree with it.

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