Grex System Problems Item

Mar 21 04:09 UTC 1999

This item is for system problems.  If something on Grex isn't working 
right (line noise on a modem, weird behavior from a program, etc.), 
this is the place to announce it.  Except for security holes.  If you 
find a hole in system security, mail information about it to "staff".

response 2 of 124:

Mar 27 20:53 UTC 1999

Sounds like Grex is really full of it. 8-)

response 4 of 124:

Mar 28 02:11 UTC 1999

The unix command is 'du'. This gets you the size of whatever directory tree
you give it. You'll have to do this for your home directory, and for your mail
file (which I am not sure that du can isolate from the rest; you might want
'ls -l /var/mail/keesan' for that.

Memory use, I'm not sure of, but 'free' gets the total memory use of the
system, including both real and virtual. There might be an option to get
memory use only for processes owned by you.

response 6 of 124:

Mar 28 14:25 UTC 1999

I did the var/spool/ thing and got about 92K.
I then typed du /a/k/e/keesan and got
226  for mail
16 for www
551 for home directory 

Does the var/spool/ thing show only mail in inbox?

response 8 of 124:

Mar 28 16:06 UTC 1999

(du shows disk usage in 512-byte blocks.  Multiply by 512 to get bytes.)

response 10 of 124:

Mar 28 18:02 UTC 1999

  but be aware that the total for "du -b" and "du -k" doesn't necessarily
  jibe..

        % du -s -k ~mcnally
        45      /a/m/c/mcnally

        % du -s -b ~mcnally
        29208   /a/m/c/mcnally

  My guess is that "du -b" just adds up the bytes in the file contents,
  which is not actually an accurate way to count how much space is being
  used by the files. 

  Files in the 4.2BSD (McKusick, et al.) filesystem being used on Grex
  consume filesystem space in greater-than-1-byte increments.  The
  filesystem is divided into "blocks", which are themselves sub-divided
  into "fragments".  Depending on how the filesystem was initialized,
  the smallest amount of disk space a file can consume will be one fragment
  (disregarding the file's entry in a directory file, which also consumes
  some space.)

  That means that if Grex's filesystems are created with 4K blocks, each
  consisting of 8 fragments (I don't know what the actual parameters are,
  I didn't create the filesystems when they were set up..) that the smallest
  amount of disk space a file can use will be 512 (= 4096 / 8) bytes(*)

  So if you have a file with just a single character in it, and assuming
  I am right about "du -b", then "ls -l" will report a size of 1 byte,
  "du -b" will count it as a byte, and "du -k" will count it as a full
  fragment -- 512(*) bytes -- a much more accurate measure of how much
  space you're really using.

  (*) again, assuming 512 byte fragments *only* for purposes of example.