Increase lvm thin what about metadata.

proxman4

New Member
Mar 23, 2020
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Hi !

Proxmox is great and i'm pretty new with this mix of technologies.

LVM is extremely powerful and i need to deal with it to increase , wisely , a thin pool without breaking anything.

Here is the situation.

I plan to enlarge a partition by 2TB.

I need to increase the thin pool used by Proxmox for VM and snapshots.

Here is the tricky step :

Do i need to increase the thin pool metadata ? If so how to proceed wisely ?

Main goal is to keep the the thin pool's metadata such larger to manage snapshots properly.

Here are the metadata :

Code:
  LV                           VG                Attr          LSize    Pool                 Origin  Data%  Meta%  Move Log Cpy%Sync Convert

  lv-mox-ply1a-thin-vm         vg-mox-ply1a-sdb4 twi-aotz--  998.00g                             90.35  54.46
  [lv-mox-ply1a-thin-vm_tdata] vg-mox-ply1a-sdb4 Twi-ao----  998.00g
  [lv-mox-ply1a-thin-vm_tmeta] vg-mox-ply1a-sdb4 ewi-ao----  128.00m

I read that lvm manage metadata automatically.

As of LVM2 2.02.89, the metadata size of the thin pool cannot be expanded, it is fixed at creation
https://wiki.gentoo.org/wiki/LVM#Thin_provisioning

So my question is :


Can i increase the lv-mox-ply1a-thin-vm and keep doing as many snapshots as vm's logical volumes ? (within)


If I'm not making myself clear i could provide more details.

Thanks in advance.

Regards.
 

Alwin

Proxmox Staff Member
Staff member
Aug 1, 2017
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329
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You can increase the data LV but not the metdata. And it the metadata will not be spread out to other PVs. Hence, if the first disks fails, also the extended part is dead.
 

proxman4

New Member
Mar 23, 2020
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1
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21
Thank you Alwin.

Finally we decided to add a partition (not enlarge) by 2TiB and we add a thin pool with separated VolumeGroup , metadata size of 2GiB and a vol_spare to be sure .

Thanks for your response.
 
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