Re: Logical Volume Manager and RAID
On Thu, 19 Jan 2006, Noah Dain wrote:
> > How does RAID interact with LVM? Do I place RAID on top of LVM or the
> > other way around?
LVM on top of md RAID (there is also device-mapper RAID, now), so lvm has
PVs that are md devices.
> > Or am I worrying unnecessarily: Is it possible to mix them arbitrariy
> > in multiple layers -- some LVM partitions on a RAID drive that's split
That's inviting trouble. I once tried LVM on top of RAID0 on top of RAID1,
and that uncovered bugs in the kernel. Even just RAID0 on top of RAID1
wasn't that stable.
One layer of md and one layer of LVM is safe. More than that, I would be
wary of. Since lvm+md_raid1 can do RAID10 (stripes over multiple mirrors),
that's what I am using now.
*Don't* layer md on top of LVM. If it works at all, it probably will be much
slower than the inverse.
> > Also -- are the file system and partition formats identical no matter
> > whether I run this Debian-only box with an AMD64 kernel or an i386
> > kernel?
AFAIK, yes.
> file system formats are the same, no matter what they are running on,
> otherwise it's no longer the same type of filesystem (ie., there would
> be ext3-32 and ext3-64, and so on).
Some filesystems are byte-order sensitive... but since ia32 and amd64 use
the same byte-order, that really wouldn't matter.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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