[ltp] HD Noise

[unlisted]

okay, i haven't tried this (i don't run linux on my thinkpad any
longer), but i just did a little research (because when i use to run
linux on my 770x this was always something that bugged me) and below is
what i found out.

background (what i already knew):

ext3 has a commit period of 5 seconds, so every five seconds any data
that needs to be written to disk, but hasn't, is written out.  this will
keep hard drives from spinning down, and make hard drives emit write
noises every 5 seconds.  in the past this was only changeable by
recompiling the ext3 code.  somewhere in there the commit interval is
defined (i think in terms of cycles, ie hertz rate times 5 seconds, so
it may not be easy to find).  this kept me running ext2 for the life of
linux on my thinkpad (nov 2001 to jan 2003).  ext2 with noflushd (it's
available as a debian package) and noatimes worked well, but not
perfectly because i had so many applications/monitors/daemons writing to
log files, that the large number of writes could only be held off for so
long (a minute or two, maybe five).  i always wanted to go to ext3
because inevitably the hardware would go spastic running under linux and
a fsck on a slow laptop hard drive is very painful (especially when
running on battery).

research (what i learned today):

here's what andrew morton (of ext3 fame) had to say about laptop hard
drives spinning up under ext3:
https://listman.redhat.com/pipermail/ext3-users/2003-January/004610.html
so, the commit period is now "tunable", and needs to be done in
cooperation with /proc/sys/vm/bdflush.

as a side note: here's a very interesting patch by him specifically for
laptops (though vm specific, and should affect all filesystems, not just
ext3), though i don't know if it every made it into the kernel (kinda
doubtful as the patch seems to have mysteriously vanished except in the
following lwn article):
http://lwn.net/Articles/1652/

search for this patch on the linux kernel mailing list and see what all
was said about it.  i only got three or four posts into the thread
before moving on.

anyways, hope this research helps somebody.  for further information
probably search google for "ext3 flush commit".

anyways...
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