[GLLUG] Link two RAIDs in one LVM?

[Dr. Axel Stammler]

Hi,

And thanks again, I have followed your advice, creating an 8TB mirrored logical volume on my two new drives, i.e. using 1 mirror = 2 copies.

On Mon 2020-05-11 13.15.55, Greater London Linux User Group wrote:
>Hi,
>
>What size are the partitions on the old 8TB disks?
>Is it a single partition for all 8TB ?
>If you have a separate data from the OS partition:
>you could "rsync -avpP"  the data/image/picture/whatever files over to
>the new disks on top of LVM.
>You could handle the OS partition offline.
>You can then do a final "catch up" rsync of the data in offline mode.
>
>Once everything is copied and you have unmounted the old disks, and
>have everything booting and running nicely on the new disks.
>You could then wipe the old disks, and redo them with LVM on them.
>
>I would allow at least a day or two for the first rsync of 8TB.

What do you think of the following procedure? Once I have copied and tested everything, I wipe the old disks and add them to the 8TB LV as copies #2 and #3. After synchronisation, I remove one of the new disks and one of the old ones, wipe them again and then extend or resize the LV to contain two pairs of mirrored 8TB data = 16TB.

As each pair would consist of an old disk combined with a new one, would the whole system not be less likely to be destroyed by two disks failing simultaneously?

What are the exact command combinations to accomplish this?

(vgextend, vgcreate, lvextend, lvresize)
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