[CentOS] Some basic LVM questions

Mon Nov 9 18:52:49 UTC 2009
Monte Milanuk <memilanuk at gmail.com>

On Mon, Nov 9, 2009 at 9:19 AM, Curt Mills <hacker at fluke.com> wrote:

>
> Perhaps skip using the 13GB drive since it will probably fail
> relatively soon.  Snag another larger drive and do mirroring between
> the two.
>

This is where I run up against a pre-conceived notion, which may or may not
be correct.  I had been thinking in terms of putting the stored data under
/srv on the larger drive(s), and if I were going to use RAID, probably
mirror those drives so if one starts acting sickly, I would have a bit of a
buffer in terms of being able to pull one drive, replace it, etc.  What
you're describing almost sounds like just having two drives period, both
500GB (for example), with /boot, /, /var, /etc, /usr, i.e. everything on
there along with the stored data, in a mirrored RAID 1 configuration.  For
whatever reason, just using RAID 1 with 'only' two drives of the same size
never occured to me... guess I thought it wasn't 'proper' or that you
needed a separate non-RAID drive for some of the system stuff like /boot...
but now that I think on it... I'm not sure why it *wouldn't* work...?  The
software RAID installation example in the CentOS 5 manual seems to indicate
doing just that, unless I'm mistaken (though they throw LVM into the mix as
well).


>
> Investigate "Amanda", "Backuppc", or "Duplicity" for doing your
> backups from the other boxes.  This way if one drive fails you have
> the other still working until you replace it and resync.  The last
> two options I listed do de-duping of the disk blocks so you're not
> duplicating the same block across backups for multiple machines.  If
> you have lots of the same files on the various machines you're
> backing up this will save you loads of space (for instance, the same
> OS on lots of machines).
>


BackupPC seems to keep coming to the top of every backup thread I've seen
recently (last year or two), so it's definitely on my list to check out -
after I get some other services (Samba) ironed out to my satisfaction.
Unfortunately, I don't think I'm going to get away with backing up the
*entire* OS or hard drive from the client computers (other than my Macbook
or the wife's Macbook from the school district, which only have 60GB hard
drives).  The daughter's new HP laptop and my HP desktop have 500GB and
640GB drives respectively.  Neither are anywhere near full yet, but I think
they may strain the meager limits of my 'server' rather soon.  My plan, such
as it is, was to back up the user directories, which is where the bulk of
the 'un-replaceable' stuff is - documents, pictures, movies, etc. vs.
programs that we have install media/codes for.  May not be ideal, but it
would be a step ahead of where I'm at currently.
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