add a pager playbook for RAID, this should really use the template

howto/raid.md

@@ -148,6 +148,25 @@ To follow progress:
 
     watch /opt/MegaRAID/MegaCli/MegaCli64  -PDRbld -ShowProg -PhysDrv[252:0] -a0
 
+## Pager playbook
+
+Nagios should be monitoring hardware RAID on servers that support
+it. This is normally auto-detected by Puppet (in the `raid`
+module/class) but grep around for `megaraid` otherwise. The `raid`
+module should have a good README file describing how it works.
+
+A normal RAID-1 Nagios check output looks like this:
+
+    OK: 0:0:RAID-1:2 drives:465.25GB:Optimal Drives:2
+
+A failed RAID-10 check output looks like this:
+
+    CRITICAL: 0:0:RAID-10:4 drives:1.089TB:Degraded Drives:3
+
+It actually has the numbers backwards: in the above situation, there
+was only *one* degraded drive, and 3 healthy ones. See above for how
+to restore a drive in a MegaRAID array.
+
 # SMART monitoring
 
 Some servers will fail to properly detect disk drives in their SMART