virajjasani commented on a change in pull request #3852:
URL: https://github.com/apache/hbase/pull/3852#discussion_r753019998
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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? Or maybe
it's only me thinking that these summary points would get more attention than
description and notes above?
```
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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