Re: [linux-lvm] Is MD array (containing a PV) reducible?

"Brian J. Murrell" <[email protected]> writes:

> Because I need to add another member to the array that is just slightly
> smaller than the existing array.  It's the same sized disk as what's in
> the array currently but is itself an MD array with luks, which is
> reserving it's own metadata region from the total disk making it
> slightly smaller.

You want to put an MD array inside of another MD array?  Why?

> So yes, ultimately I am going to have both an encrypted and unencrypted
> member of this raid-1 array.  At least until the encrypted member is
> added and then I will remove the unencrypted member and add it to the
> luks encrypted array.
>
> The general idea is to (safely -- as in be able to achieve in specific
> sepearate steps that have a back-out plan) convert a non-encrypted
> raid-1 array into an encrypted raid-1 array.
>
> So what I have right now is:
> sdc                                             8:32   0   3.7T  0 disk  
> └─md0                                           9:0    0   3.7T  0 raid1 
>   ├─backups-backups                           253:13   0   2.5T  0 lvm   /.snapshots
>   ├─backups-borg                              253:14   0   300G  0 lvm   
>   └─backups-vdo--test                         253:15   0   700G  0 lvm   
>     └─vdo-backups                             253:73   0   1.8T  0 vdo   
> sdd                                             8:48   0   3.7T  0 disk  
> └─md1                                           9:1    0   3.7T  0 raid1 
>   └─luks-backup                               253:40   0   3.7T  0 crypt 

I would suggest that rather than

> I am going to reduce the size of md0 so that it's the same size as md1,
> then add md1 to md0 (so yes, I will have a raid-1 array with a raid-1
> member).  Then I am going to remove md0 from the md1 array and then add
> sdc to md1 so that md0 no longer exists and md1 is the primary raid-1
> array.  Ideally, rename md1 to md0 once done but that's aesthetic.

I would suggest instead that you add the luks volume as a new PV to your
VG, then use pvmove to migrate all of your logical volumes from md0 to
md1, then vgreduce md0 from the VG, stop md0, mdadm --zero-superblocks
/dev/sdc, then add sdc to md1.

_______________________________________________
linux-lvm mailing list
[email protected]
https://listman.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/