The ESXi server or VMs on the ESXi become unresponsive during virtual machine backups. You may need to restart the ESXi server manually. You could also run into this issue while upgrading the VMware backup proxy. You can see errors when you log into the VMware backup proxy console.
blk_update_request: I/O Error,
Buffer I/O error on dev loop1,
eth0: tx hang , TX ABORT
You may encounter this issue when the datastore runs out of space or with vCenter ESXi 6.5 where vMotion is enabled.
- Free up space on the datastore if it has run out of space.
- If you are on ESXi 6.5 with vMotion enabled, see VMware documentation for the known issue resolution.