qm: add documentation for vm network MTU setting

[pve-docs.git] / pvecm.adoc

diff --git a/pvecm.adoc b/pvecm.adoc
index 97a665be2504f8cf129e65d9994c5a164620c303..4bf2d53ceb8843ef71db67a70cb661450d90352a 100644 (file)
--- a/pvecm.adoc
+++ b/pvecm.adoc
@@ -58,7 +58,7 @@ Grouping nodes into a cluster has the following advantages:
 Requirements
 ------------
 
-* All nodes must be able to connect to each other via UDP ports 5404 and 5405
+* All nodes must be able to connect to each other via UDP ports 5405-5412
  for corosync to work.
 
 * Date and time must be synchronized.
@@ -1051,6 +1051,8 @@ The SSH key from the cluster will be automatically copied to the QDevice.
 
 NOTE: Make sure that the SSH configuration on your external server allows root
 login via password, if you are asked for a password during this step.
+If you receive an error such as 'Host key verification failed.' at this
+stage, running `pvecm updatecerts` could fix the issue.
 
 After you enter the password and all the steps have successfully completed, you
 will see "Done". You can verify that the QDevice has been set up with:
@@ -1257,6 +1259,26 @@ it is likely that some nodes will boot faster than others. Please keep in
 mind that guest startup is delayed until you reach quorum.
 
 
+[[pvecm_next_id_range]]
+Guest VMID Auto-Selection
+------------------------
+
+When creating new guests the web interface will ask the backend for a free VMID
+automatically. The default range for searching is `100` to `1000000` (lower
+than the maximal allowed VMID enforced by the schema).
+
+Sometimes admins either want to allocate new VMIDs in a separate range, for
+example to easily separate temporary VMs with ones that choose a VMID manually.
+Other times its just desired to provided a stable length VMID, for which
+setting the lower boundary to, for example, `100000` gives much more room for.
+
+To accommodate this use case one can set either lower, upper or both boundaries
+via the `datacenter.cfg` configuration file, which can be edited in the web
+interface under 'Datacenter' -> 'Options'.
+
+NOTE: The range is only used for the next-id API call, so it isn't a hard
+limit.
+
 Guest Migration
 ---------------