Re: LVM root?

[Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de>]

dtutty@porchlight.ca writes:

> In Debian, is it only the loss of / that requires a reinstall?  What
> happens if /var (especially /var/lib) or /usr get corrupted?  Doesn't
> that also make the system extremely difficult/time-consuming to restore?
>
> If I were to get a second 80 GB SATA drive so that I could raid1 /,
> might I just as well have the whole base system on raid1?  

Yes, that is best. The loss of / or /var is pretty much the same. A
lot of work to recover. /usr (excluding /usr/local) can be recovered
easily though. Just get the list of installed packages from
/var/lib/dpkg/ and reinstall all of them. But it is still nuisance to
have to do so.

> I would then have something like this:
>
> Disk a:
> Part:	Size:	
> 1	64MB	
> 5	remainder
>
> Disk b:
> Part:	Size:
> 1	64 MB
> 5	remainder
>
> a1 and b1 raid1 to make md0 and mounted as /boot
> 	since can't resize md0, can anyone imagine /boot ever needing 
> 	more than 64 MB to hold 2 kernels (old and new)?
> 	Boot will be via grub installed on both drive's mbrs for
> 	auto-failover booting.
> a5 and b5 raid1 to make md0 which becomes pv0 of vg0
> lvs made for rest of base system including /
> This also ends up with swap in a lv on raid1 so drive crash shouldn't
> crash the system.

Unless it crashes the controler or driver (which can easily happen
with inexpensive non hardware raid) in the process the system will
keep working. If in doubt get a hotplug carrier for your drive and
pull one out while running.

> If this looks good, do the d-i menus let me start out with a degraded
> raid1 with only one drive, and add the second drive later?

I'm not sure and would say no if I have to guess. But try and if not
try creating the raid in degraded mode on the second console.

> Thanks to your patient help, I'm gradually getting my head around this
> new world.  Thank you.
>
> Doug.

MfG
        Goswin