Re: to lvm or not to lvm?
On Fri, 2007-04-20 at 19:42 -0400, Douglas Allan Tutty wrote:
> On Fri, Apr 20, 2007 at 10:37:35AM -0500, Default User wrote:
> > Hi!
> >
> > After installing fresh Etch with encrypted lvm (all except /boot), per
> > non-expert install, I am reconsidering whether lvm is a good idea. It
> > works fine - now - but what if it stops working?
> >
> > The only partition that seems to be accessible from a sarge system on
> > the same machine is the /boot partition. If Etch decides to misbehave,
> > how would I be able to access my data? Or is this a case of "you do
> > back up your data every day, don't you?"
> >
> > I really do like the ability to resize my partitions as needed (the
> > layout that seemed fine upon install can really look stupid 6 months
> > later). But not at the price of my data.
> >
> > And does encryption of lvm partitions unnecessarily complicate matters,
> > especially recovery? Would just an encrypted swap partition only be
> > better?
> >
>
> As always, it depends :)
>
> What is the threat that you are trying to avoid. Personally, if nothing
> else, I like swap encrypted (random key, no need for boot up pass
> phrase), with /tmp on tmpfs.
>
> As for accessing an LVM setup that 'stops working', it depends on why it
> stopped working. The Etch installer CD has a good rescue mode that can
> access the LVM stuff and help with fixes to common problems.
>
> This, too, requires you to look at the over-all threat. If you have a
> concern about drive failure, then LVM alone isn't what you want; you
> want LVM over software raid.
>
> In the absence of a drive failure, what can make LVM 'stop working'?
> Some people have reported problems with device renaming (eg sda1 to
> sde1). Someone who has solved that problem can tell you how to avoid it
> in the first place. Since I have my system LVs on raid1, the md mapper
> checks all disks it finds for the md config block; it doesn't rely on
> drive names; LVM then just looks for md0.
>
> So try rephrasing the question. Tell us what your threat concerns are.
>
> Doug.
>
>
intended use: standard home system, single user, not mission critical
(except that to everyone, their own data is always "mission critical").
nothing exotic or fancy.
do really need lvm? if i have to ask, then the answer is, "probably
not". my concern was that a partition that seems spacious originally,
can over time become cramped, while another loafs with unused space. and
no one can precisely predict future needs. further, i plan to switch to
testing after the chaos dies down, and want to run that at least until
lenny becomes the next stable. so i am trying to think long term. and
re-installing every 6 months would really get old fast.
i could just have one / partiton (plus a swap partition). That's simple,
flexible, and low maintenance. no worrying about data outgrowing
partition sizes. but the OpenBSD FAQ makes a compelling case for
multiple partitions, at least separate /, /tmp, /var, /usr, and /home
(as well as an ENCRYPTED swap partition). and that is one of the default
partitioning choices in the Debian installer.
note: I am not trying to start an OS flame war. I just mention it for
what it's worth.
a fresh install is a rare opportunity to do things right, so I try not
to squander it.
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