VMs boot extremely slowly on specific hosts, the booting process mainly stuck in the phrase when vm icon changes from yellow to blue

1. Run" #tap-ctl list" hang on the target hosts
2. Run "#strace -e trace=all tap-ctl list" to locate the hang process pid
3. Run "#ll /proc/pid/fd" to check the iso file which the hang process is related to
4. Run "#umount -fl /var/run/sr-mount/<uuid_of_iso_storage>" on all host to manually umount the iso mount information
5. Confirm that HA is not enabled on the resource pool, then restart toolstack service on the pool master
6. Reconnect the resource pool back to XenCenter, manually eject the iso file from target VMs
7. Forget the ISO storage from XenCenter

Problem Cause

The ISO storage has been removed from the environment , but the ISO files are still attached to some running VMs