Fedora 15, new and exciting plans (LVM issues)

[Dennis Jacobfeuerborn]

On 11/15/2010 12:00 AM, John Reiser wrote:
> On 11/14/2010 01:13 PM, Matt McCutchen wrote:
>> On Sun, 2010-11-14 at 13:07 -0800, John Reiser wrote:
>>> When I created 14 partitions using a DOS partition label
>>> (3 primaries, plus extended containing 10 logical partitions)
>>> and gave 6 of the partitions to an LVM setup,
>>> then I could not remove one of the partitions from the clutches
>>> of the LVM, and use the removed partition for some other purpose
>>> (keeping the rest of the LVM going), unless I removed all the LVM
>>> from that drive.
>>
>> vgreduce + pvremove?  Did something go wrong when you tried?
>
> vgreduce would not let go of the partition that I wanted to take back,
> claiming that the partition was still in use.
> -----
> DESCRIPTION
>         vgreduce allows you to remove one or more *unused* physical volumes
>         from a volume group.  [emphasis added]
> -----
> I could not find a way to evict any usage of that partition (transparently
> move the information somewhere else in the same LVM) as a prelude to applying
> vgreduce.  In theory I could have moved all of the LVM onto another drive,
> but I wanted to keep the LVM going on that drive, with the same user-visible
> information content [there was enough free space], but without using one
> particular partition that I had given [loaned] to LVM some time before.
>

pvmove is the command you need to use before doing a vgreduce. That's 
basically what I did with the 30TB system that I mentioned elsewhere in 
this thread. This system was partitioned into 10 raid-5 volumes and one of 
those acted up when we put the system into production (it was already 
pre-filled with data). So what I did was a pvmove to clear out the physical 
volume which took a few hours and then I removed the physical volume from 
the volume group. The fact that I could do all of this while the system 
stayed online and was being used was a real life saver.

Regards,
   Dennis