test WP failed, assume write enabled

[degenhardt]

All 20 seconds these messages appear in /var/log/messages

May 9 23:27:51 proxmox kernel: sd 9:0:0:2: reservation conflict
May 9 23:27:51 proxmox kernel: sd 9:0:0:2: [sdd] Test WP failed, assume Write Enabled //// Any ideas what could cause this ? We have proxmox kernel 2.3 running on Debian 6.0.7