[linux-lvm] SAN setup with host mirrored disks

Luca Berra bluca at comedia.it
Thu Jul 13 17:15:54 UTC 2006

On Thu, Jul 13, 2006 at 12:04:01AM +0200, Fiederling, Daniel wrote:
>I'm relatively new to SAN setup with linux boxes, so maybe this is a
>very easy question. Today I set up a linux box with two qlogic hbas,
>each one is connected to a EMC Clarion. So I got two disks (/dev/sda and
>/dev/sdb) from my storages that I have to mirror on the host system.
>There is on mirror set up in the san environment!
>How can I set up mirroring of the two disks if I want to use lvm for the
>ease of later disk expansion? If I use raidtools (md-stuff) will it be
do not use raidtools, it is an obsolete tool. use mdadm if you want md.

>possible to expand the two disks and the logical disk without data loss?

>What are the needed steps if I have to increase the disk space? First
>expand the md devices through raidreconf and then expand the volume

you can use a recent mdadm with the --grow option instead of raidreconf

another option is to create and additional lun instead of enlarging the
current one, lvm will handle a vg on multiple pvs just fine.

>Is it possible to use lvm for mirroring physical volumes? If this is
>possible I expect that this will be the better solution.

recent lvm2 support mirroring of logical volumes, so you could use this
it is a relatively new feature and i did not test it personally, so
maybe someone else on the list can give you more feedback.


Luca Berra -- bluca at comedia.it
        Communication Media & Services S.r.l.
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