swap to a sparse file

[Steve O'Hara-Smith]

On Fri, 12 Oct 2018 19:36:33 +0100
RW via freebsd-questions <freebsd-questions at freebsd.org> wrote:

> On Thu, 11 Oct 2018 08:51:14 +0100
> Steve O'Hara-Smith wrote:
> 
> > On Thu, 11 Oct 2018 08:47:05 +0700
> > Victor Sudakov <vas at mpeks.tomsk.su> wrote:
> > 
> > > Is there any good reason I can't just "truncate -s2G /swap0" and
> > > make the swap a sparse file?   
> > 
> > 	Just one - if the space isn't there when the system needs it
> > there will be a panic.
> 
> Is that really the only reason? I've not paid much attention, but the
> warnings I've heard about this have made it sound a lot worse.

	There's not much worse the system can do than panic, other than
deadlock which might happen if memory needs to be allocated in order to add
blocks to the file. IIRC swap on a zvol can deadlock that way.

-- 
Steve O'Hara-Smith <steve at sohara.org>