Re: [concept & "good taste" review] persistent store

[Huang Ying]

On Tue, 2010-12-21 at 18:10 +0800, David Howells wrote:
> Huang Ying <ying.huang@xxxxxxxxx> wrote:
> 
> > > > - for OOPS messages will not cause system panic, it will go to disk and
> > > > will not use up the persistent storage.
> > > 
> > > You can't guarantee that an oops didn't just kill your ability to actually
> > > write your syslog to disk or out across the network.
> > 
> > I do not need to guarantee that. If the OOPS message can not be written
> > to disk, just keeping it in persistent storage, and that is the very
> > value of persistent storage.  But for OOPS can go to disk safely, we do
> > not need to waste persistent storage for it.
> 
> My point is how do you know an oops message will actually manage to get to
> disk?  There's a userspace program (syslogd) between the kernel log and the
> disk or network.

The user space program (syslogd) is in my big picture, it will guarantee
an oops meesage actually go to disk via something like fsync.  After
doing that, the user space program can erase the corresponding record in
persistent storage to free the space.  So all in all, oops messages not
causing system panic or disk error will go to disk eventually and being
freed and will not use up the persistent storage.

Best Regards,
Huang Ying


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