Changeset 1462

Timestamp:

Oct 31, 2008, 2:00:19 PM (16 years ago)

Author:

broder

Message:

Add some additional documentation on how the sysvm disk locking works

File:

• trunk/packages/invirt-xen-config/debian/invirt-xen-config.init (modified) (1 diff)

trunk/packages/invirt-xen-config/debian/invirt-xen-config.init

@@ -40 +40 @@
     
     if lvchange -a n "$DISK" >/dev/null 2>&1 && lvchange -a ey "$DISK" >/dev/null 2>&1; then
-        # If we can lock on the VM's disk, then the VM isn't running
+        # If we can disable and then re-enable the VMs disk, then the
+        # VM can't be running. If the lvchange -a ey succeeds, then we
+        # have an exclusive lock across the cluster on enabling the
+        # disk, which avoids the potential race condition of two hosts
+        # starting a VM at the same time
         [ "$VERBOSE" != no ] && log_daemon_msg "Starting sysvm $VM"
         xm create "sysvms/$VM" >/dev/null