Is bin ever written to?

[Loïc Grenié]

2008/12/23 Knapp <magick.crow at gmail.com>:
> On Tue, Dec 23, 2008 at 8:22 PM, Smoot Carl-Mitchell <smoot at tic.com> wrote:
>> On Tue, 2008-12-23 at 20:05 +0100, Knapp wrote:
>>> I was wondering if anything in a set up system ever needs to write to
>>> /bin or /sbin or /usr/bin or /usr/sbin?
>>> I was thinking of putting them in a ram disk with SquashFS to speed up
>>> the system but it can only read and not write.
>>> As far as I know the only time writing is needed is with a system update.
>>
>> You are correct.  The only time the "bin" directories are written is
>> during system updates.
>>
>> I am not sure how much improvement you will see by putting the common
>> system commands in a ram disk.  The demand paging system keeps
>> frequently accessed pages in memory anyway. The only way to know is to
>> try it and see what kind of improvement you see.
>> --
>> Smoot Carl-Mitchell
>
> Any other ideas of what might best be on a ram disk?
> All the hidden home files was suggested because programs like FF might
> be speeded up and then at shutdown the ramdisk could be written to the
> home dir. This posses a risk, if there is a power outage but other
> than that should be safe.

    The kernel writers usually says that it's much better to NOT use a ramdisk
  and let the kernel do the cache (it's also much safer in case of power
  outage). You lose the first time you read a file, but the rest of the time it
  remains in memory (in you read it often). Except if you have a very
  specific use, you'd better not put anything on your ramdisk and not do
  any ramdisk.

     The first time you read a file, the kernel copies it into memory.
It remains
  there unless there is not enough memory for the rest of the system. In that
  case the least used files are canceled from memory. This means that the
  kernel will create a "virtual ramdisk" in the cache where all the
files that you
  use often will remain. Each of those "usual" files will be read only
once during
  each normal session. If you use all your memory for some memory intensive
  program, the cache will be canceled, but your memory will be available for
  your program (which will not, or less, swap) instead of being locked for a
  ramdisk.

           Loïc