From 4d20a3810697042f34db3e2ad671f8296f23c646 Mon Sep 17 00:00:00 2001
From: erthalion <9erthalion6@gmail.com>
Date: Tue, 5 Jun 2018 11:42:01 +0200
Subject: [PATCH] Add section about volume increase

---
 docs/user.md | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/docs/user.md b/docs/user.md
index d0ebcc1b0..7647ef71f 100644
--- a/docs/user.md
+++ b/docs/user.md
@@ -242,3 +242,34 @@ metadata:
 
 Note that timezone required for `timestamp` (offset relative to UTC, see RFC
 3339 section 5.6)
+
+## Increase volume size
+
+PostgreSQL operator supports statefulset volume resize if you're using the
+operator on top of AWS. For that you need to apply manifest with a new size,
+and the operator will find out that a volume size needs to be changed:
+
+```
+apiVersion: "acid.zalan.do/v1"
+kind: postgresql
+
+metadata:
+  name: acid-test-cluster
+spec:
+  volume:
+    size: 5Gi # new volume size
+```
+
+You can only increase a volume size in this way, if a new requested size is
+smaller than the previous one nothing will be done. After this update all the
+new pods in a statefulset will be created with a new volume size. To increase a
+volume size on already existing pods in a statefulset, the operator will
+perform the following steps:
+
+* modify EBS volume size
+
+* resize an actuall filesystem use `resize2fs`
+
+Note that if before a volume size was increased a statefulset was scaled down
+and (after the change was applied) scaled back, those pods that were down will
+have an old volume size, since a statefulset doesn't delete volumes.