[libvirt-users] lvm vs qcow (on NVMe)

[lejeczek]

hi guys,

anybody observed, maybe has measured performance difference between the
two with qemu quests(windows OS)?

Any conclusions, recommendations?

many thanks, L.

[Kashyap Chamarthy]

Post by lejeczek
hi guys,
anybody observed, maybe has measured performance difference between
the two with qemu quests(windows OS)?
Any conclusions, recommendations?

[Cc Stefan from QEMU, probably he might have some pointers.]

[Stefan Hajnoczi]

Post by Kashyap Chamarthy

Post by lejeczek
hi guys,
anybody observed, maybe has measured performance difference between
the two with qemu quests(windows OS)?
Any conclusions, recommendations?

[Cc Stefan from QEMU, probably he might have some pointers.]

You can get good performance with qcow2 if you preallocate the image
file:

$ qemu-img create -f qcow2 -o preallocation=falloc vm001.qcow2 10G

Writing to new regions of the image has a higher cost without
preallocation. The downside is that the storage will be reserved for
the disk image so you no longer start off with a tiny file that grows on
demand. That's the trade-off if performance is critical.

Stefan