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Improve documentation for snapshots 

patch by Abi Palagashvili; reviewed by Stefan Miklosovic and Brandon Williams for CASSANDRA-16887

Co-authored-by: akihiro17 <akihiro17@users.noreply.github.com>
Co-authored-by: Stefan Miklosovic <smiklosovic@apache.org>
This commit is contained in:
fibersel 2024-01-25 11:11:01 +01:00 committed by Stefan Miklosovic
parent f6707e6191
commit c5a023a204
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8 changed files with 105 additions and 3 deletions
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2
doc/modules/cassandra/examples/BASH/nodetool_clearsnapshot_all.sh
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@ -1 +1 @@
$ nodetool clearsnapshot -all cqlkeyspace
$ nodetool clearsnapshot --all cqlkeyspace

27
doc/modules/cassandra/examples/RESULTS/cqlsh_list_snapshots.result Normal file
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@ -0,0 +1,27 @@
cqlsh> expand on;
EXPAND set to ON
cqlsh> select * from system_views.snapshots ;
@ Row 1
---------------+---------------------------------
name | catalog-cql-ks
keyspace_name | catalogkeyspace
table_name | journal
created_at | 2024-01-25 10:06:41.420000+0000
ephemeral | False
expires_at | 2024-01-25 10:09:41.420000+0000
size_on_disk | 6279
true_size | 1143
@ Row 2
---------------+---------------------------------
name | catalog-cql-ks
keyspace_name | catalogkeyspace
table_name | magazine
created_at | 2024-01-25 10:06:41.420000+0000
ephemeral | False
expires_at | 2024-01-25 10:09:41.420000+0000
size_on_disk | 1125
true_size | 1125
(2 rows)

3
doc/modules/cassandra/examples/RESULTS/nodetool_list_snapshot_empty.result Normal file
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@ -0,0 +1,3 @@
$ nodetool listsnapshots
Snapshot Details:
There are no snapshots

5
doc/modules/cassandra/examples/RESULTS/nodetool_list_snapshots_ephemeral.result Normal file
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@ -0,0 +1,5 @@
$ nodetool listsnapshots -e
Snapshot Details:
Snapshot name Keyspace name Column family name True size Size on disk Creation time Expiration time Ephemeral
catalog-cql-ks catalogkeyspace magazine 1.1 KiB 1.1 KiB 2024-01-25T10:01:59.745Z 2024-01-25T10:04:59.745Z false
catalog-cql-ks catalogkeyspace journal 1.12 KiB 6.13 KiB 2024-01-25T10:01:59.745Z 2024-01-25T10:04:59.745Z false

3
doc/modules/cassandra/examples/RESULTS/nodetool_snapshot_help.result
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@ -42,6 +42,9 @@ OPTIONS
-t <tag>, --tag <tag>
The name of the snapshot
--ttl <ttl>
Specify a TTL of created snapshot
-u <username>, --username <username>
Remote jmx agent username

4
doc/modules/cassandra/examples/RESULTS/nodetool_snapshot_list_ttl_snapshots.result Normal file
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@ -0,0 +1,4 @@
$ nodetool listsnapshots
Snapshot Details:
Snapshot name Keyspace name Column family name True size Size on disk Creation time Expiration time
catalog-journal catalogkeyspace journal 1.12 KiB 6.13 KiB 2024-01-25T09:45:31.820Z 2024-01-25T09:48:31.820Z

3
doc/modules/cassandra/examples/RESULTS/nodetool_snapshot_take_ttl.result Normal file
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@ -0,0 +1,3 @@
$ nodetool snapshot --tag catalog-journal --ttl 3m catalogkeyspace.journal
Requested creating snapshot(s) for [catalogkeyspace.journal] with snapshot name [catalog-journal] and options {skipFlush=false, ttl=3m}
Snapshot directory: catalog-journal

61
doc/modules/cassandra/pages/managing/operating/backups.adoc
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@ -312,6 +312,63 @@ results in
include::cassandra:example$RESULTS/nodetool_list_snapshots.result[]
----
It is also possible to list all snaphots including so-called _ephemeral_ snapshots. These are
technical snapshots internal to Cassandra which are normally deleted after a particular operation is done.
If `-e` flag is used when listing snapshots, a new column will be added to the output telling if a snapshot is
ephemeral or not:
[source, bash]
----
include::cassandra:example$RESULTS/nodetool_list_snapshots_ephemeral.result[]
----
[NOTE]
====
You can not manually remove ephemeral snapshots.
====
It is also possible to list snapshots via `system_views.snapshots` virtual table:
[source, cql]
----
include::cassandra:example$RESULTS/cqlsh_list_snapshots.result[]
----
=== Expiring snapshots
It is possible to set a time-to-live (TTL) for a created snapshot using the `--ttl` option, causing that snapshot
to be automatically cleaned up when the TTL expires. TTL can be specified in minutes (m), seconds (s), hours (h)
and days (d). The example below shows the creation of a snapshot for all tables in the `catalogkeyspace`
and `cqlkeyspace` keyspaces with a TTL of 3 minutes:
[source,bash]
----
include::cassandra:example$RESULTS/nodetool_snapshot_take_ttl.result[]
----
now let's display information about snapshots:
[source,bash]
----
include::cassandra:example$RESULTS/nodetool_snapshot_list_ttl_snapshots.result[]
----
We see creation and expiration time. Let's wait a couple of minutes and try again:
[source,bash]
----
include::cassandra:example$RESULTS/nodetool_list_snapshot_empty.result[]
----
Finally, these snapshots have expired.
[NOTE]
====
If you take a snapshot with TTL and stop Cassandra node and you start it again by the
time that snapshot would be expired, Cassandra will automatically delete it upon its start.
====
=== Finding Snapshots Directories
The `snapshots` directories may be listed with `find –name snapshots`
@ -363,7 +420,7 @@ include::cassandra:example$RESULTS/snapshot_files.result[]
=== Clearing Snapshots
Snapshots may be cleared or deleted with the `nodetool clearsnapshot`
command. Either a specific snapshot name must be specified or the `–all`
command. Either a specific snapshot name must be specified or the `--all`
option must be specified.
For example, delete a snapshot called `magazine` from keyspace `cqlkeyspace`:
@ -373,7 +430,7 @@ For example, delete a snapshot called `magazine` from keyspace `cqlkeyspace`:
include::cassandra:example$BASH/nodetool_clearsnapshot.sh[]
----
or delete all snapshots from `cqlkeyspace` with the –all option:
or delete all snapshots from `cqlkeyspace` with the `--all` option:
[source,bash]
----