regroup known issues

howto/ganeti.md

@@ -38,9 +38,6 @@ See also the more extensive [glossary in the Ganeti documentation](http://docs.g
 
 ## Adding a new instance
 
-WARNING: this creates a machine with usrmerge! See [bug 34115](https://bugs.torproject.org/34115)
-before proceeding.
-
 This command creates a new guest, or "instance" in Ganeti's
 vocabulary:
 
@@ -57,12 +54,6 @@ vocabulary:
       --backend-parameters memory=8g,vcpus=2 \
       test-01.torproject.org
 
-WARNING: there is a bug in `ganeti-instance-debootstrap` which
-misconfigures `ping` (among other things), see [bug #31781](https://bugs.torproject.org/31781). It's
-currently patched in our version of the Debian package, but that patch
-might disappear if Debian upgrade the package without [shipping our
-patch](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=944538).
-
 ### What that does
 
 This configures the following:
@@ -100,20 +91,30 @@ Also set reverse DNS for both IPv4 and IPv6 in [hetzner's robot](https://robot.y
 
 Then follow [howto/new-machine](howto/new-machine).
 
-### When the allocator fails
+### Known issues
+
+ * **usrmerge**: that procedure creates a machine with usrmerge! See
+   [bug 34115](https://bugs.torproject.org/34115) before proceeding.
 
-Note that you may need to use the `--node` parameter to pick on which
-machines you want the machine to end up, otherwise Ganeti will choose
-for you (and may fail). Use, for example, `--node fsn-node-01:fsn-node-02` to use
-`node-01` as primary and `node-02` as secondary. It might be better to
-let the Ganeti allocator do its job since it will, eventually do this
-during cluster rebalancing. The allocator can sometimes fail if the
-allocator is upset about something in the cluster, for example:
+ * **allocator failures**: Note that you may need to use the `--node`
+   parameter to pick on which machines you want the machine to end up,
+   otherwise Ganeti will choose for you (and may fail). Use, for
+   example, `--node fsn-node-01:fsn-node-02` to use `node-01` as
+   primary and `node-02` as secondary. The allocator can sometimes
+   fail if the allocator is upset about something in the cluster, for
+   example:
     
-    Can's find primary node using iallocator hail: Request failed: No valid allocation solutions, failure reasons: FailMem: 2, FailN1: 2
+        Can's find primary node using iallocator hail: Request failed: No valid allocation solutions, failure reasons: FailMem: 2, FailN1: 2
+
+   This situation is covered by [ticket 33785](https://bugs.torproject.org/33785). If this problem
+   occurs, it might be worth [rebalancing the cluster](#Rebalancing-a-cluster).
+
+ * **ping failure**: there is a bug in `ganeti-instance-debootstrap`
+   which misconfigures `ping` (among other things), see [bug
+   31781](https://bugs.torproject.org/31781). It's currently patched in our version of the Debian
+   package, but that patch might disappear if Debian upgrade the
+   package without [shipping our patch](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=944538).
 
-This situation is covered by [ticket 33785](https://bugs.torproject.org/33785). If this problem
-occurs, it might be worth [rebalancing the cluster](#Rebalancing-a-cluster).
 
 ## Modifying an instance