[PVE-User] RBD move disk : what about "sparse" blocks ?

Alexandre DERUMIER aderumier at odiso.com
Tue May 7 08:26:55 CEST 2019


>>Is there any way to copy *exactly* disk from one pool to another, using 
>>PVE live disk moving ? 

It's currently not possible with ceph/librbd. (it's missing some pieces in qemu librbd driver)


>>Of course when I run "fstrim -va" on the guest, I can't reclaim space 
>>because kernel thinks it was already trimmed (while on source pool).

It should works without any problem. I have done it a thousand time.
fstrim do trim again and again a each run,for the whole disk.
(vs /etc/fstab discard option, which is doing it live only)


as workaround, we have added an option in the qemu-agent, to do fstrim for you just after move disk

----- Mail original -----
De: "Florent Bautista" <florent at coppint.com>
À: "proxmoxve" <pve-user at pve.proxmox.com>
Envoyé: Mardi 7 Mai 2019 00:47:48
Objet: [PVE-User] RBD move disk : what about "sparse" blocks ?

Hi, 

I have a strange situation while moving disks stored on RBD pools. 

I move from one pool to another (replicated pool to EC pool). 

For example, I have a 16GB disk, using 3131.12 MB on the replicated 
source pool (command : rbd diff pve01-rbd02/vm-206-disk-1 | awk '{ SUM 
+= $2 } END { print SUM/1024/1024 " MB" }' ) 

When PVE has moved the disk on the destination EC pool, disk is now 
using 16384 MB. 

Of course when I run "fstrim -va" on the guest, I can't reclaim space 
because kernel thinks it was already trimmed (while on source pool). 

Is there any way to copy *exactly* disk from one pool to another, using 
PVE live disk moving ? 

Thank you. 

Florent 

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