Is it really necessary to run swapoff on shutdown?
smithi at nimnet.asn.au
Mon Aug 24 13:43:30 UTC 2015
In freebsd-questions Digest, Vol 585, Issue 5, Message: 21
On Fri, 21 Aug 2015 11:52:04 +0100 Mike Clarke <jmc-freebsd2 at milibyte.co.uk> wrote:
> I have two 4GB swap partitions on separate drives on my desktop. By
> the time I shut down at the end of the day I usually have about 8% swap
> in use.
> At an early stage in the shutdown /etc/rc.d/swaplate runs
> and takes about one minute to run '/sbin/swapoff -aq'. On some occasions
> when more swap has been used swapoff has failed to complete before
> timing out.
I guess you could extend the shutdown timeout as a poor workaround?
> Perhaps I'm misunderstanding the finer details of managing swap space
> but I would have expected that swapoff could be omitted on shutdown. As
> each process shuts itself down it will retrieve any swapped out pages
> which it needs so by the time the last process is finished none of
> the remaining data in the swap space will be required by anything and
> can be safely discarded.
Sounds good in theory, but dragons may caution 'shoulds' for 'wills' ..
> Also if it really is necessary to run swapoff on shutdown should the
> command have also included the -L option to allow for it having been
> used in the swapon command.
I know nothing, except noticing that the recent thread 'Swap Questions'
in -stable@ explores some perhaps related issues, including use of '-L'
More information about the freebsd-questions