Merge pull request #7017 from gyuho/faq

dev-guide: add limit.md

Documentation/dev-guide/limit.md

@@ -0,0 +1,10 @@
+# System limits
+
+## Request size limit
+
+etcd is designed to handle small key value pairs typical for metadata. Larger requests will work, but may increase the latency of other requests. For the time being, etcd guarantees to support RPC requests with up to 1MB of data. In the future, the size limit may be loosened or made it configurable.
+
+## Storage size limit
+
+The default storage size limit is 2GB, configurable with `--quota-backend-bytes` flag; supports up to 8GB.
+

Documentation/docs.md

@@ -17,6 +17,7 @@ The easiest way to get started using etcd as a distributed key-value store is to
  - [gRPC naming and discovery][grpc_naming]
  - [Embedding etcd][embed_etcd]
  - [Experimental features and APIs][experimental]
+ - [System limits][system-limit]
 
 ## Operating etcd clusters
 
@@ -60,6 +61,7 @@ Answers to [common questions] about etcd.
 [api_grpc_gateway]: dev-guide/api_grpc_gateway.md
 [clustering]: op-guide/clustering.md
 [conf]: op-guide/configuration.md
+[system-limit]: dev-guide/limit.md
 [common questions]: faq.md
 [data_model]: learning/data_model.md
 [demo]: demo.md
@@ -84,4 +86,4 @@ Answers to [common questions] about etcd.
 [versioning]: op-guide/versioning.md
 [supported_platform]: op-guide/supported-platform.md
 [experimental]: dev-guide/experimental_apis.md
-[v3_upgrade]: upgrades/upgrade_3_0.md
+[v3_upgrade]: upgrades/upgrade_3_0.md