[PVE-User] SAN and correctly propagate 'discard'...

Alexandre DERUMIER aderumier at odiso.com
Tue Oct 9 16:54:19 CEST 2018

>>Clearly i cannot use 'LVM Thin', because is not shared. 
>[ https://pve.proxmox.com/wiki/Storage:_LVM_Thin | https://pve.proxmox.com/wiki/Storage:_LVM_Thin ] 
>>Someone can give me some clue? Thanks.

Indeed, LVM thin can't work with shared SAN, only on local disk.
So you can't have thin provisioning, and can't use discard.

It's just not possible, sorry.

----- Mail original -----
De: "Marco Gaiarin" <gaio at sv.lnf.it>
À: "proxmoxve" <pve-user at pve.proxmox.com>
Envoyé: Mardi 9 Octobre 2018 15:12:18
Objet: [PVE-User] SAN and correctly propagate 'discard'...

My SAN (HP MSA 1040) have 'virtual volume' enabled, eg discard. 

I've had to use directly some LUN in some VM, via iSCSI, and 'fstrim' 
works as expected. 

Now i'm using for some disks in my VMs, as storage of type 'LVM'. 

But if i look at disk space on SAN, it is coherent with the real disk 
space occupied. 
While, in Proxmox, the storage volume are full or near full. 

Example, VM: 
root at vdmsv1:~# df -h | grep sdc 
/dev/sdc1 800G 519G 282G 65% /home 
/dev/sdc2 1000G 152G 848G 16% /srv 

Proxmox node: 
root at tessier:~# pvesm status | grep DATA0 
DATA0 lvm 1 1953120256 1887436800 65683456 97.14% 
root at tessier:~# pvesm list DATA0 
DATA0:vm-120-disk-1 raw 1932735283200 120 

and SAN report 730GB allocated. 

Clearly disks of VM have 'discard' enabled, but seems that discard/trim 
does not ''traverse'' all the storage chains (partition in the VM, 
LV/PV/VG in proxmox node, iSCSI in the SAN). 

Clearly i cannot use 'LVM Thin', because is not shared. 


Someone can give me some clue? Thanks. 

dott. Marco Gaiarin GNUPG Key ID: 240A3D66 
Associazione ``La Nostra Famiglia'' http://www.lanostrafamiglia.it/ 
Polo FVG - Via della Bontà, 7 - 33078 - San Vito al Tagliamento (PN) 
marco.gaiarin(at)lanostrafamiglia.it t +39-0434-842711 f +39-0434-842797 

(cf 00307430132, categoria ONLUS oppure RICERCA SANITARIA) 
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