[SunHELP] a question

velociraptor velociraptor at gmail.com
Fri Aug 27 14:18:26 CDT 2004

On Fri, 27 Aug 2004 12:12:47 -0700, velociraptor <velociraptor at gmail.com> wrote:
> You are referring to "minfree" reserved by mkfs when the partition is
> created.  UFS (and other file systems) have provided minfree or
> similar options for a while; it is not new.  Nor is it "protective"
> other than giving the system administrator an early warning sign. It
> will not prevent the machine from having problems when any key system
> (/, /var, /tmp, swap) partition fills up.
> For instance, if swap fills up (more likely if /tmp is on swap), then
> the machine's performance will deteriorate dramatically, even if it
> can still spawn processes.
> <http://www.princeton.edu/~psg/unix/Solaris/troubleshoot/ram.html>
> <http://sunsolve.sun.com/pub-cgi/show.pl?target=content/content8>
> If /var fills up you may not be able to su to root even if you are
> logged into the box.  The computer may even crash.
> It's fairly common to reduce the minfree on a partition if it's a
> large user-oriented partition--the 10% default wastes a huge amount of
> space when working with partitions over 100GB.

Also, where you put your partitions can dramatically affect
performance.  If the system disk is a single disk with all system
partitions on it, or key system partitions are mirrored, this will
have a big effect on the performance of applications should their
default be to write logs or temporary files to system partitions.

For example: the default for popper (POP3 mail) is to put the copy of
the user's mail spool into /tmp when they fetch their mail over
POP3...and it copies the entire mail spool when it does this.  Now
multiply this times 100 users with mail spools of +100MB...


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