Re: [linux-lvm] LVM and fault tolerance

[Anders Widman <andewid@tnonline.net>]

Lars Kellogg-Stedman wrote:

> > Is there any possibility to add fault tolerance to LVM. I would like
> > to span several disks (of different sizes) and have fault tolerance to
> > it. Also, most important, is to be able to extend it with additional
> > disks without loosing data.
>
> Disclaimer: I've only recently started working with LVM under Linux.
>
> That said, I think that the general solution to fault tolerance is to
> combine LVM with either (a) the software RAID (md) subsystem, or (b)
> hardware RAID devices.
>

Well, it will have to be software RAID (limited budget)

>
> For example, you can create a number of md devices, using RAID1 or RAID5
> for fault tolerance, and then run pvcreate on them and manage them with
> lvm.
>
> I'm doing this right now with a 4-disk RAID5 array (3 disks + 1 hot
> spare), and it seems to be working just fine.
>

So, how is this actually working then. Let say I have this disk
configuration:

2x 40gb
2x 60gb
2x 80gb

I want maximum amount of diskspace available for storage. High speed is not
needed at all as this is mainly for storage and streaming low bitrate media.
Still, I need to be able to add additional disks, maybe two extra 80gb
disks. Would it be possible to keep ecc/crc data on one disk only, or stripe
it over all disks. Mirroring is to expensive in this sence too.

The problem with RAID-5 is that all disks need to be of the same size and
that it is not expandable (or is it?).

//Anders

>
> -- Lars
>
> --
> Lars Kellogg-Stedman <lars@larsshack.org>
>
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