[CentOS] unable to umount

Hi,

on an EL5 XEN DOM0 system I have following volume

$ df -h /srv Filesystem Size Used Avail Use% Mounted on /dev/sdc1 917G 858G 60G 94% /srv

that partition was used by virtual machines but they were all halted.

service xendomains stop

$ xm list Name ID Mem(MiB) VCPUs State Time(s) Domain-0 0 3000 2 r----- 695.1

$ service xend stop

nothing is using the partition $ lsof |grep srv <empty>

$ fuser -m /srv <empty>

$ fuser -km /srv <empty>

but i can not umount /srv

$ umount /srv umount: /srv: device is busy umount: /srv: device is busy

what could keeping the device "busy" ... ?

__ Thanks,

LF