[linux-lvm] RAID 1 on Device Mapper - best practices?

[Mike Williams]

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On Friday 17 October 2003 21:07, John Stoffel wrote:

> Anyway, what I'd like to do is setup the disks using Device Mapper so
> that I can grow and shrink volumes at need, along with the filesystems
> mounted on top of those volumes.  So I now have it working, except
> that reboots don't detect the RAID volumes on top of the Device Mapper
> LVs properly on reboot.

> Nor do I think I'm really doing this in the proper way.  Currently I
> have one volume group per disk, left_vg and right_vg.  Each has a pair
> of LVs on then, [left,right]_lv_[home,local] for a total of four LVs.
>
> Then I assemble these into MD volumes using mdadm, with each volume
> having an LV from each of the VGs.
>
> Do I really need to use MD here, or can I build a mirrored LV to do
> what I want?

Wouldn't it be more sensible to mirror the disks, then stick your LVs on top 
of that? This is what I have done with a software RAID5 array.

At first this didn't work, as the startup scripts Gentoo provide initialise 
LVM before MD, but that was easily changed.

- -- 
Mike Williams
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