Re: [dm-devel] [PATCH 2/2] dmcache: Implement a flush message

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, May 13, 2013 at 02:04:08PM +0200, Peter Rajnoha wrote:
> On 11.05.2013 17:25, Mike Snitzer wrote:> On Fri, May 10 2013 at  1:51pm
> -0400,
> > Darrick J. Wong <darrick.wong@oracle.com> wrote:
> >
> ...
> >> afaict, there isn't anything in the initscripts that tears down dm
> devices
> >> prior to invoking reboot(), and the kernel drivers don't have reboot
> notifiers
> >> to flush things out either.  I've been told that lvm does this, but I
> don't see
> >> anything in the Ubuntu or RHEL6 that would suggest a teardown script...
> >
> > See:
> https://git.fedorahosted.org/cgit/lvm2.git/commit/?id=c698ee14bbb1310cf2383c8977d14a8e29139f8c
> >
> > But I'm not sure which distros have hooked blkdeactivate in (cc'ing
> > prajnoha for his insight).
> >
> 
> The blk-availability initscript/systemd unit that gets called at
> shutdown/reboot and which in turn calls the blkdeactivate is already
> used in RHEL 6.4 onwards and also in Fedora 18 onwards. However, for
> Fedora, you need to enable the systemd unit explicitly at the moment
> (systemctl enable blk-availability.service). To have it enabled by
> default, the distro-wide default systemd configuration needs to be
> edited which is controlled by systemd-preset file (I hope F19 is going
> to have this enabled by default finally).
> 
> As for any other distros, it's up to the maintainers in that distro to
> make use of the new script - I haven't looked if they started using it
> or not. But upstream already provides it since lvm2 v2.02.98.

Aha!  Thank you for providing the missing link.  Now it all makes sense. :)

(fwiw Ubuntu's latest is 2.02.95.)

--D
> 
> Peter
> 
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