diff --git a/notes/cockroachUnsync.png b/notes/cockroachUnsync.png
new file mode 100644
index 0000000000000000000000000000000000000000..a1dfc6c45d5a7d1a232b6da5bd22838f1b1175ac
Binary files /dev/null and b/notes/cockroachUnsync.png differ
diff --git a/notes/spannerCockroach.md b/notes/spannerCockroach.md
index c51e1dc846a4a8791d37a589e3bcbadef427ce1a..4ed6ac7e863796368fd5ca0ac1efbfdd2eb8eadf 100644
--- a/notes/spannerCockroach.md
+++ b/notes/spannerCockroach.md
@@ -108,6 +108,9 @@ without atomic clocks."
 regardless of observer, provides for a particularly strong guarantee of
 external consistency known as “linearizability.”
 - "in a non-distributed database, serializability implies linearizability"
+  - single clock
+  - if T2 starts after T1 finishes, that will be equiv serial order, and so...
+![blah](cockroach1.png)
 - "CockroachDB’s external consistency guarantee is by default only
   serializability, though with some features that can help bridge the gap in
   practice."