[PVE-User] performance issue for synchronised I/O with qcow2 disk images on ZFS

[Stephane Chazelas]

Hello,

in case you're experiencing very bad synchronised disk I/O
performance (like when updating/installing debian packages) in
QEMU guests, and you're using qcow2 disk images stored on ZFS
file systems, you may want to watch this thread on the QEMU
devel mailing list:

https://www.mail-archive.com/qemu-devel@nongnu.org/msg427170.html

A work-around for now is to revert the pve-qemu-kvm package to
2.6.2 version (anything before 2.7).

-- 
Stephane