[CentOS] How often is kernel "touching" swap partition?

wolfy at corewolf.org wolfy at corewolf.org
Tue Jul 23 21:18:37 UTC 2013


You know that you don't need a swap partition for hibernation?
s2disk(uswsusp) makes a swapfile on your hdd prior to hibernating and 
only activates it for hibernation purposes, so you don't have to have 
swap active all the time.

On 2013-07-23 20:28, Martin Šťastný wrote:
> Thank you for you responses,
> 
> first of all I need same amount of swap space as of memory, because I 
> want
> to use hibernation. Problem of placing swap partition on SSD is not 
> with
> too many writes, but with to much space used for nothing (in my case 8 
> GB,
> 16 GB in not so far future). I know about "swappiness" kernel tunable, 
> but
> I guess it has nothing to do with how often is partition "simply 
> touched
> for nothing" and therefore hard drive is spinned up. For example - if I 
> set
> HDD to spin down after two minutes and kernel will touch swap 
> approximately
> every five minutes, it means that hard drive will be spinned up 120 
> times
> every day (10 hours of power on), 43 800 cycles per year which will
> definitely wreck my HDD :-(.
> 
> 2013/7/23 Jorge Fábregas <jorge.fabregas at gmail.com>
> 
>> On 07/23/2013 01:22 PM, Martin Šťastný wrote:
>> >  how often is kernel touching swap space
>> 
>> There's a kernel tunable called "swappiness" [1] to control that.  You
>> can add an entry in /etc/sysctl.conf like this:
>> 
>> vm.swappiness=0
>> 
>> ...and the kernel will avoid, as much as it can, to use swap.
>> 
>> HTH,
>> Jorge
>> 
>> [1]: http://en.wikipedia.org/wiki/Swappiness
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