Re: [gentoo-user] Rearranging hard drives and data.

[Dale <rdalek1967@gmail.com>]

antlists wrote:
> On 19/12/2020 17:32, Dale wrote:
>> Neil Bothwick wrote:
>>> On Sat, 19 Dec 2020 07:02:23 -0600, Dale wrote:
>>>
>>>> I have another question related to LVM.  Let's say a system crashes
>>>> and
>>>> dies.  Or I just move a drive, or drives, with LVM on it to another
>>>> system.  Does the system just recognize the drives and knows how to
>>>> add
>>>> them or do I have to do that manually on the new system?
>>> It should just work if you move all the PVs in the volume group. One
>>> thing to watch out for is if the destination system is already using
>>> LVM,
>>> the volume groups must be named differently. That's why I always use
>>> unique VG names based on the hostname.
>>>
>>
>> Ahhh, so it stores the info on the drive so that it knows what it is.
>> Neato!!  I was thinking it was in /etc/lvm/ or something.  I've wondered
>> about that for a while now.
>
> mdadm version 0 stored its information in mdadm.conf. That was a
> mistake - it had the downside you couldn't boot from the array, it was
> wide open to errors, arrays were regularly trashed because things had
> got confused, etc etc. Sticking all the necessary information in a
> superblock is now considered must-do good practice.
>>
>> Naming them based on hostname is also a good idea.  I don't have mine
>> named that way but if I ever redo them, I will.  It could save me some
>> problems down the road.
>>
> Again, that's now the default for mdadm - not necessarily the user
> name, but the internal array name is something like "tigger:0", to
> quote one of mine - array 0 created on tigger.
>
> Cheers,
> Wol
>
>


Right now, this is mine:


root@fireball / # vgs
VG            #PV #LV #SN Attr   VSize    VFree 
Home2        2   1   0 wz--n-  <12.74t      0
OS               1   3   0 wz--n- <124.46g <35.46g
backup        1   1   0 wz--n-  698.63g      0
root@fireball / #


I'm assuming it would be best to have them named like this:


root@fireball / # vgs
VG            #PV #LV #SN Attr   VSize    VFree 
fb-Home2        2   1   0 wz--n-  <12.74t      0
fb-OS               1   3   0 wz--n- <124.46g <35.46g
fb-backup        1   1   0 wz--n-  698.63g      0
root@fireball / #


The added fb would be short for fireball.  If this rig suddenly blew a
gasket and I stuck the drives in a new system, it would make them
different at least.  Once moved and stable, Neil says I can rename it to
something else to match the new system.  It sounds like a good idea
since right now, I could move those drives to a system that has the same
names which would cause issues.  As a matter of fact, the reason for
Home2 is because I already had a Home group in a previous move.  I guess
we are talking about the same thing.

Dale

:-)  :-)