virajjasani commented on a change in pull request #3852:
URL: https://github.com/apache/hbase/pull/3852#discussion_r753019998
##########
File path: src/main/asciidoc/_chapters/ops_mgt.adoc
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@@ -3150,23 +3150,24 @@ TTL some notion of optional TTL (and optional default
TTL) for snapshots could b
hbase> snapshot 'mytable', 'snapshot1234', {TTL => 86400}
----
-The above command creates snapshot `snapshot1234` with TTL of 86400 sec(24
hours)
+The above command creates snapshot `snapshot1234` with TTL of 86400 sec (24
hours)
and hence, the snapshot is supposed to be cleaned up after 24 hours
.Default Snapshot TTL:
-
-- FOREVER by default
-- User specified Default TTL with config `hbase.master.snapshot.ttl`
-
-
-While creating a Snapshot, if TTL in seconds is not specified, by default the
snapshot
-would not be deleted automatically. i.e. it would be retained forever until it
is
-manually deleted. However, the user can update this default TTL behavior by
-providing default TTL in sec for key: `hbase.master.snapshot.ttl`.
-Value 0 for this config indicates TTL: FOREVER
-
+- User specified default TTL with config `hbase.master.snapshot.ttl`
+- FOREVER if `hbase.master.snapshot.ttl` is not set
+
+While creating a snapshot, if TTL in seconds is not explicitly specified, the
above logic will be
+followed to determine the TTL. If no configs are changed, the default behavior
is that all snapshots
+will be retained forever (until manual deletion). If a different default TTL
behavior is desired,
+`hbase.master.snapshot.ttl` can be set to a default TTL in seconds. Any
snapshot created without
+an explicit TTL will take this new value.
+
+NOTE: If `hbase.master.snapshot.ttl` is set, a snapshot with an explicit {TTL
=> 0} or
+{TTL => -1} will also take this value. In this case, a TTL < -1 (such as {TTL
=> -2} should be used
+to indicate FOREVER.
Review comment:
Thanks @joswiatek.
Looks good. After this line, shall we sum up with these points?
```
To sum-up,
1. Snapshot with TTL value < -1 will stay forever regardless of any server
side config changes (until deleted manually by user).
2. Snapshot with TTL value > 0 will be deleted soon after TTL expires.
3. Snapshot created without specifying TTL will always have TTL value
represented by config `hbase.master.snapshot.ttl`. Default value of this config
is 0, which represents: keep the snapshot forever (until deleted manually by
user).
4. From client side, TTL value 0 or -1 should not be provided because they
will be treated same as snapshot without TTL (same as above point 3) and hence
will use TTL as per value represented by config `hbase.master.snapshot.ttl`.
```
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