[svlug] Partitioning problem

[James Sparenberg]

On Tue, 2006-02-07 at 11:04 -0800, Don Marti wrote:
> begin Rick Moen quotation of Mon, Feb 06, 2006 at 02:28:37PM -0800:
> > Quoting Don Marti (dmarti at zgp.org):
> > 
> > > Any experience with swapping to software RAID?
> > 
> > None.  Do you think I might be better off (1) putting the second swap on
> > /dev/sdb4, and not mirroring that?  Or maybe (2) sticking with swap only
> > on /dev/sda6 and skipping any swap on the other drive pair?
> 
> The only time my machines hit swap much is when a
> long-running large program gets paged back in, which
> is typically when I'm opening a large image in the
> GIMP after having worked on other stuff for a while.
> I don't see any swapping on the servers.
> 
> It seems as Today, performance considerations for
> swap really only seem to matter if you have big
> applications that you want to leave running while
> you let the kernel use physical memory for disk cache.
> 
> (Martin Pool on "Is swap space obsolete?"...
> 
> http://sourcefrog.net/weblog/software/linux-kernel/swap.html
> 

Speaking annecdotally only I've actually had a condition where I
recently rebuilt a server (File services (samba and NSF) as well as
nagios PXE and internal web pages.  The box had 7 drives 1 for OS and 6
in and ext3 LVM (bad choice of FS but I won't go there) With 1GB of ram
no one had ever notice the biggest mistake made when it was originally
built.  It had no active swap partition.  Space was on the first drive
for this, but, it had never been formated or activated (no swap
partition in fstab.)  This box ran Fedora Core 2 so it had been running
for quite a while without a swap related problem since it came online
originally. 

This really serves as a real world example of how low the importance of
swap can be in many situations. 

One thing I'm sure that helped was the fact that on this box nothing
that was uneeded was ever running.  In RH style use of Run Levels it ran
at run level 3 (No graphical environment) and all unused processes were
turned off (good security anyway) So nothing went to waste.  But even
long process like updatedb (it was a 1.4T box) didn't get slowed down or
become ram starved.

James