[CentOS] Constant disk activity

Woodchuck marmot at pennswoods.net
Thu Mar 22 02:35:53 EDT 2012


On Thu, Mar 22, 2012 at 01:06:41PM +0800, Fajar Priyanto wrote:
> On Thu, Mar 22, 2012 at 12:45 PM, dnk <d.k.emaillists at gmail.com> wrote:
> > It is old. 512 Mb ram, 1.6 Ghz (Celeron), 2 X 1TB Dell 7200 RPM Sata drives. Mostly backup purposes (rsync and crashplan). transmission-daemon running. That's about it at this point.
> >
> 
> 512MB is pretty low. I wont be surprised that it's doing swapping all the time.
> Try to stop and disable all services you can from:
> chkconfig --list
> 
> Moreover, that transmission daemon is surely causing disk activity,
> don't you think so?

Give me 512MB and I will compute forever :-)

It is doubtful that the machine is swapping, just sitting there
running X+gnome or KDE. But why would it swap?  Idle processes don't
swap.  If anything, idle pages get swapped out, and stay swapped
out.

The simplest way to check is with 
	# swapon -s	 (man swapon)

Swapping can be observed as it occurs with top(1) or iotop(1) (the
latter from packages).  The simplest way to reduce the memory load
on this machine, if it is used as a server for backups and so on,
is to not run X on it.  This is accomplished with:
        # telinit 3     (man telinit)

No need to reboot or other windoze-style shenanigans.  There is
never a sound reason to reboot except catastrophic failure or a
kernel update.  And there is no need to run X to run most X
applications, if they display on another machine's console. (How-to
do this is fairly easy, but OT).  If this doesn't free up memory,
nothing will.

The machine can be trained to boot up in runstate 3, (networking
and multiuser, no X) by editing /etc/inittab:
	# vi /etc/inittab	(man telinit vi)
Change the line:
	id:5:initdefault:
to
	id:3:initdefault:

I believe the sequence of commands would be  Gf5r3ZZ

Presto. Changeo. Fixo.

The machine can be admined from its console, or if headless, via
ssh or even over a serial port.  Yeah, you can start X/gnome/KDE/Xcruft
on a headless machine, I think, and that stuff starts by default on
CentOS out-of-the-box. Usually.

What is this transmission daemon of which you speak?

Dave
-- 
   "If government had taken over the auto industry in 1920, today we'd
   all be driving Model-T cars -- and saying, 'If it weren't for the
   government, we'd have no cars at all.'"     -- Harry Browne


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