[SOLVED] Shrinking lvm disk

N6rV1UUV · 05-22-2019, 04:42 AM

I want to shrink lvm partitioned disk and clone it to a smaller one.
I did

Code:

lvreduce -L XXG

and then tried shrinking it with gparted which failed due to segment allocation.

Code:

pvs -v --segments /dev/sdb2

gives this result:

https://i.postimg.cc/zGJdHt5w/Screen...1-08-50-46.png

Code:

pvmove --alloc anywhere /dev/sdb2:16577-27615 /dev/sdb2:11457-22495

fails because free SSize is too small.
How do I make free segments appear on the end of PV table?

rknichols · 05-22-2019, 09:50 AM

That's because pvmove cannot handle overlapping moves.

The simplest thing to do would be to move just the last 5120 segments of the centos-root LV to the currently free region:

Code:

pvmove /dev/sdb2:22506-27615 /dev/sdb2:11457-16576

That has the disadvantage of making the segments of the centos-root LV even more out of sequence physically than they are now.

You can do the move in several stages of 5120 segments at a time (like playing the 15-tile-puzzle game), but frankly I would, instead of cloning, just create a new PV on the target disk and then pvmove the segments of all LVs from your current disk to the locations where you want them on the new disk:

Code:

vgextend centos /dev/sdb2
pvmove /dev/sda2:0-9695 sdb2:0-9695
pvmove /dev/sda2:16577-27615 /dev/sdb2:9696-20734
pvmove /dev/sda2:9696-11456 /dev/sdb2:20735-22495

That will put your LVs on the new disk, with the root filesystem segments back in order.

syg00 · 05-22-2019, 05:46 PM

I always like to keep a backup. I would mirror to the new disk then break the mirror.