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

[max]

Andrew Haley wrote:
> max bianco wrote:
>> On Tue, Jun 10, 2008 at 4:38 PM, Andrew Haley <aph at redhat.com> wrote:
>>> max bianco wrote:
>>>> On Tue, Jun 10, 2008 at 9:46 AM, Chuck Anderson <cra at 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