newbie problem with hard disk space...

Bryan Breen Bryan.C.Breen.1 at gsfc.nasa.gov
Wed Jan 29 12:27:23 PST 2003


>> Not true. When that command was executed my uptime was about 25 days
>> 14hrs or so (power outage knocked it down....d'oh!). The issue that I
>> would imagine that keeps me from using swap is that my LFS system is a
>> router/server and only has sshd, proftpd, and folding at home running. At
>> the time I ran `free` there were no active ftp connections and the
>> only active ssh one was myself.
>
>must be a very light server, or the buffering from open files would have
>pushed at least some things into swap by now.

If I Recall Correctly:

Buffering files will not cause portions of memory to be pushed into swap.
Yes, it will eventually fill up all free RAM, but any additional buffering
will simply overwrite in RAM the buffered data that was the used the
farthest in the past. If a buffered file was written to the swap, which is
almost always on a hard disk, then there'd be no performance benefit from
reading it again from the original file, over reading it from the swap. For
that reason, the "overflow" of buffered data is just dumped.

The only way you are going to get any noteworthy amount of data into the
swap is by having multiple processes loaded simultaneously that consume
enough RAM in total to push one or more of the processes into the swap.

 The main processes that were listed as running don't take up much memory
at all (just a few dozen megabytes at most), so they are probably never
going to trigger a swap hit, regardless of how long the server runs. (And I
can attest to this behavior from first hand experience with a server
running a similar processor load for over 250 days that never touched its
swap but always had all but a scant few kilobytes of the RAM gobbled up by
buffered data.)
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