Re: LVM negates benefits of jounaling filesystems? [was RFE: autofsck]

[max <maximilianbianco gmail com>]

Andrew Haley wrote:
> max bianco wrote:
> > On Tue, Jun 10, 2008 at 4:38 PM, Andrew Haley <aph redhat com> wrote:
> > > max bianco wrote:
> > > > On Tue, Jun 10, 2008 at 9:46 AM, Chuck Anderson <cra wpi edu> wrote:
> > > > > On Tue, Jun 10, 2008 at 08:36:31AM -0500, Eric Sandeen wrote:
> > > > > > journaling filesystem you really shouldn't have any filesystem metadata
> > > > > > integrity problems on power loss; that is, if you have barriers on
> > > > > > (which ext3 doesn't by default) and if your storage can pass barriers
> > > > > > (which lvm doesn't), or if you have drive write cache disabled (which
> > > > > > hurts performance pretty badly).
> > > > > I wasn't aware that LVM destroyed the kind of guarantees about
> > > > > filesystem metadata being written out to disk that jounaling
> > > > > filesystems rely on?  If so, should we perhaps rethink the decision to
> > > > > use LVM by default on Fedora installs?
> > > > What was the reason for using LVM in the first place. My most recent
> > > > install I was really tempted to not go with the defaults but because I
> > > > really don't know much about filesystems, I figured the best thing in
> > > > that case was stick to the defaults. Now I am reconsidering
> > > > again...could someone explain the comparative advantages/disadvantages
> > > > ? Before i do something stupid .
> > > LVM has a lot of advantages with regard to flexibility: you can add a
> > > disk to a filesystem, for example.  It has a lot of nice features.
>
> > but there seems to be some question as to data integrity or ability to
> > recover data in the event of disaster or am i reading too much into
> > this?
>
> Yes, you are.  The question here is about barriers, which are off by
> default in ext3 anyway.  If you're worried about disaster recovery, you
> need to be looking at backup and replication.
>
> Andrew.

I am the victim of the poorly worded question, due entirely to my own 
ignorance on the subject but I did a little poking around so I'll have 
another go at it. Is disaster recovery more difficult with an LVM than 
the older standard partioning scheme?

--
Revenge is for the ignorant