I put cloudvirt1015 into service on Monday the 8th. Yesterday (the 11th) tools-prometheus-01 crashed with a kernel panic. On Friday 12th, tools-worker-1023 also crashed.
On Saturday 13th, @Zppix's puppet-lta.lta-tracker.eqiad.wmflabs crashed
We've replaced lots of parts in this box, to no avail: