Re: [gentoo-user] RAID/LVM machine - install questions

[Mark Knecht]

On Sat, Mar 20, 2010 at 6:22 AM, Florian Philipp
<lists@f_philipp.fastmail.net> wrote:
> Am 19.03.2010 23:40, schrieb Mark Knecht:
> [...]
>>
>>    The LVM Install doc is pretty clear about not putting these in LVM:
>>
>> /etc, /lib, /mnt, /proc, /sbin, /dev, and /root
>>
>
> /boot shouldn't be there, either. Not sure about /bin
>
>> which seems sensible. From an install point of view I'm wondering
>> about RAID and how I should treat /, /boot and swap? As I'm planning
>> on software RAID it seems that maybe those part of the file system
>> should not even be part of RAID. Is that sensible? I always want /
>> available to mount the directories above. /boot on RAID means (I
>> guess) that I'd need RAID in the kernel instead of modular, and why do
>> I need swap on RAID?
>>[...]
>
> If you use kernel based software RAID (mdadm, not dmraid), you can put
> everything except of /boot on RAID. Even for /boot, there are
> workarounds. I think there was a thread about it very recently right on
> this list.

I'm thinking I'll keep it as simple as possibly and just spread out
the Gentoo install over the multiple hard drives without using RAID,
but maybe not. It would be nice to have everything on RAID but I don't
know if I should byte that off for my first taste of building RAID.


>
> If you don't want to use an initrd (and believe me, you don't), you
> cannot build the RAID components as modules, of course. But why would
> you want? You need it anyway all the time between bootup and shutdown.

No initrd. I've never used it in 10 years of running Linux and I
wouldn't know how to start or even why I would use it. I suppose if I
had hardware RAID then maybe I'd need to but that's not my plan.

>
> You don't need to put swap on a RAID. Swap has its own system for
> implementing RAID-1 or RAID-0-like functionality. Using a RAID-1 for it
> prevents the machine from crashing if the disk on which swap resides
> dies. RAID-0 would be faster, of course.
>
> I personally find it easier to put swap on LVM in order to make
> management easier. However, if you want to use suspend-to-disk (a.k.a.
> hibernate), you would need an initrd, again.
>
> Alternatively, you can also use LVM for mirroring (RAID-1) or striping
> (RAID-0) single volumes. I think this only makes sense if you just want
> to protect some single volumes. After using it for some time, I found it
> not worth the effort. With current disk prices, just mirror everything
> and live easy ;-)
>
> Hope this helps,
> Florian Philipp
>
>

Very helpful. Thanks!

Cheers,
Mark