[CentOS] Adding RAM

John jses27 at gmail.com
Wed Dec 10 15:22:41 UTC 2008


On Tue, 2008-12-09 at 12:07 -0500, Ross Walker wrote:
> On Dec 9, 2008, at 10:59 AM, Matt <lm7812 at gmail.com> wrote:
> 
> >>>> Setting scheduler is global in C4 it can be set as a kernel option
> >>>> with a scheduler=deadline in grub.
> >>>
> >>> Is that an alias for "elevator=deadline" (which I know works)?
> >>
> >> No that was me forgetting the option name.
> >>
> >> Thanks Peter, it's elevator= not scheduler=
> >
> > Does this mean I need to add "elevator=deadline" to grub.conf?  Is
> > there a way to make the change without rebooting?
> 
> I'm afraid not, so possibly a late night or weekend event with the  
> option for a mid day reboot to recover if things turn out badly.
> 
> Virtualize things and you can minimize downtime with snapshots.

[root at blah ~]# cat /sys/block/hda/queue/scheduler
noop anticipatory deadline [cfq]   
The Schedular is CFQ and can be changed on the fly to whatever Block
Device you want it. It does not matter what load the system is under.
Changing to Deadline on his specific block device will improve the I/O
of the system unless it really being hammered. Keep in mind these
changes will be gone on Reboot. You can put these in rc.local to
activate at boot time. Substitute "hda" for your device. This does not
work on iscsi or SAN mounts.

[root at blah ~]# echo 'deadline' > /sys/block/hda/queue/scheduler
[root at blah ~]# cat /sys/block/hda/queue/scheduler
noop anticipatory [deadline] cfq  -- Changed to Deadline.

JohnStanley




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