Hello, Not sure if it's a bug or a limitation but, while playing with oVirt 4.1 new possibilities, I tried to use the sparsity function on a preallocated disk, and this action irreversibly ruined the data on the disk. I have repeated this experiment multiple times and always same result. (Sparsifying a thin provisioned disk works great though) I understand that the "sparsify" function is relevant to thin provision disks only. Still I think there should be a warning before doing this action on a preallocated disk? or maybe even forbid this action on a preallocated disk since sparsify has no meaning on a preallocated disk? (I maybe wrong...) thanks cordialement, regards, Nelson LAMEIRAS Ingénieur Systèmes et Réseaux / Systems and Networks engineer Tel: +33 5 32 09 09 70 nelson.lameiras@lyra-network.com www.lyra-network.com | www.payzen.eu