mirror of
https://github.com/ceph/ceph
synced 2024-12-22 03:22:00 +00:00
7151415801
Introduced-by: https://github.com/ceph/ceph/pull/53070 Fixes: https://tracker.ceph.com/issues/65350 Signed-off-by: Milind Changire <mchangir@redhat.com>
210 lines
9.4 KiB
ReStructuredText
210 lines
9.4 KiB
ReStructuredText
.. _snap-schedule:
|
|
|
|
==========================
|
|
Snapshot Scheduling Module
|
|
==========================
|
|
This module implements scheduled snapshots for CephFS.
|
|
It provides a user interface to add, query and remove snapshots schedules and
|
|
retention policies, as well as a scheduler that takes the snapshots and prunes
|
|
existing snapshots accordingly.
|
|
|
|
|
|
How to enable
|
|
=============
|
|
|
|
The *snap_schedule* module is enabled with::
|
|
|
|
ceph mgr module enable snap_schedule
|
|
|
|
Usage
|
|
=====
|
|
|
|
This module uses :doc:`/dev/cephfs-snapshots`, please consider this documentation
|
|
as well.
|
|
|
|
This module's subcommands live under the `ceph fs snap-schedule` namespace.
|
|
Arguments can either be supplied as positional arguments or as keyword
|
|
arguments. Once a keyword argument was encountered, all following arguments are
|
|
assumed to be keyword arguments too.
|
|
|
|
Snapshot schedules are identified by path, their repeat interval and their start
|
|
time. The
|
|
repeat interval defines the time between two subsequent snapshots. It is
|
|
specified by a number and a period multiplier, one of `h(our)`, `d(ay)`,
|
|
`w(eek)`, `M(onth)` and `y(ear)`. E.g. a repeat interval of `12h` specifies one
|
|
snapshot every 12 hours.
|
|
The start time is specified as a time string (more details about passing times
|
|
below). By default
|
|
the start time is last midnight. So when a snapshot schedule with repeat
|
|
interval `1h` is added at 13:50
|
|
with the default start time, the first snapshot will be taken at 14:00.
|
|
The time zone is assumed to be UTC if none is explicitly included in the string.
|
|
An explicit time zone will be mapped to UTC at execution.
|
|
The start time must be in ISO8601 format. Examples below:
|
|
|
|
UTC: 2022-08-08T05:30:00 i.e. 5:30 AM UTC, without explicit time zone offset
|
|
IDT: 2022-08-08T09:00:00+03:00 i.e. 6:00 AM UTC
|
|
EDT: 2022-08-08T05:30:00-04:00 i.e. 9:30 AM UTC
|
|
|
|
Retention specifications are identified by path and the retention spec itself. A
|
|
retention spec consists of either a number and a time period separated by a
|
|
space or concatenated pairs of `<number><time period>`.
|
|
The semantics are that a spec will ensure `<number>` snapshots are kept that are
|
|
at least `<time period>` apart. For Example `7d` means the user wants to keep 7
|
|
snapshots that are at least one day (but potentially longer) apart from each other.
|
|
The following time periods are recognized: `h(our)`, `d(ay)`, `w(eek)`, `M(onth)`,
|
|
`y(ear)` and `n`. The latter is a special modifier where e.g. `10n` means keep
|
|
the last 10 snapshots regardless of timing,
|
|
|
|
All subcommands take optional `fs` argument to specify paths in
|
|
multi-fs setups and :doc:`/cephfs/fs-volumes` managed setups. If not
|
|
passed `fs` defaults to the first file system listed in the fs_map.
|
|
When using :doc:`/cephfs/fs-volumes` the argument `fs` is equivalent to a
|
|
`volume`.
|
|
|
|
When a timestamp is passed (the `start` argument in the `add`, `remove`,
|
|
`activate` and `deactivate` subcommands) the ISO format `%Y-%m-%dT%H:%M:%S` will
|
|
always be accepted. When either python3.7 or newer is used or
|
|
https://github.com/movermeyer/backports.datetime_fromisoformat is installed, any
|
|
valid ISO timestamp that is parsed by python's `datetime.fromisoformat` is valid.
|
|
|
|
When no subcommand is supplied a synopsis is printed::
|
|
|
|
#> ceph fs snap-schedule
|
|
no valid command found; 8 closest matches:
|
|
fs snap-schedule status [<path>] [<fs>] [<format>]
|
|
fs snap-schedule list <path> [--recursive] [<fs>] [<format>]
|
|
fs snap-schedule add <path> <snap_schedule> [<start>] [<fs>]
|
|
fs snap-schedule remove <path> [<repeat>] [<start>] [<fs>]
|
|
fs snap-schedule retention add <path> <retention_spec_or_period> [<retention_count>] [<fs>]
|
|
fs snap-schedule retention remove <path> <retention_spec_or_period> [<retention_count>] [<fs>]
|
|
fs snap-schedule activate <path> [<repeat>] [<start>] [<fs>]
|
|
fs snap-schedule deactivate <path> [<repeat>] [<start>] [<fs>]
|
|
Error EINVAL: invalid command
|
|
|
|
Note:
|
|
^^^^^
|
|
A `subvolume` argument is no longer accepted by the commands.
|
|
|
|
|
|
Inspect snapshot schedules
|
|
--------------------------
|
|
|
|
The module offers two subcommands to inspect existing schedules: `list` and
|
|
`status`. Bother offer plain and json output via the optional `format` argument.
|
|
The default is plain.
|
|
The `list` sub-command will list all schedules on a path in a short single line
|
|
format. It offers a `recursive` argument to list all schedules in the specified
|
|
directory and all contained directories.
|
|
The `status` subcommand prints all available schedules and retention specs for a
|
|
path.
|
|
|
|
Examples::
|
|
|
|
ceph fs snap-schedule status /
|
|
ceph fs snap-schedule status /foo/bar --format=json
|
|
ceph fs snap-schedule list /
|
|
ceph fs snap-schedule list / --recursive=true # list all schedules in the tree
|
|
|
|
|
|
Add and remove schedules
|
|
------------------------
|
|
The `add` and `remove` subcommands add and remove snapshots schedules
|
|
respectively. Both require at least a `path` argument, `add` additionally
|
|
requires a `schedule` argument as described in the USAGE section.
|
|
|
|
Multiple different schedules can be added to a path. Two schedules are considered
|
|
different from each other if they differ in their repeat interval and their
|
|
start time.
|
|
|
|
If multiple schedules have been set on a path, `remove` can remove individual
|
|
schedules on a path by specifying the exact repeat interval and start time, or
|
|
the subcommand can remove all schedules on a path when just a `path` is
|
|
specified.
|
|
|
|
Examples::
|
|
|
|
ceph fs snap-schedule add / 1h
|
|
ceph fs snap-schedule add / 1h 11:55
|
|
ceph fs snap-schedule add / 2h 11:55
|
|
ceph fs snap-schedule remove / 1h 11:55 # removes one single schedule
|
|
ceph fs snap-schedule remove / 1h # removes all schedules with --repeat=1h
|
|
ceph fs snap-schedule remove / # removes all schedules on path /
|
|
|
|
Add and remove retention policies
|
|
---------------------------------
|
|
The `retention add` and `retention remove` subcommands allow to manage
|
|
retention policies. One path has exactly one retention policy. A policy can
|
|
however contain multiple count-time period pairs in order to specify complex
|
|
retention policies.
|
|
Retention policies can be added and removed individually or in bulk via the
|
|
forms `ceph fs snap-schedule retention add <path> <time period> <count>` and
|
|
`ceph fs snap-schedule retention add <path> <countTime period>[countTime period]`
|
|
|
|
Examples::
|
|
|
|
ceph fs snap-schedule retention add / h 24 # keep 24 snapshots at least an hour apart
|
|
ceph fs snap-schedule retention add / d 7 # and 7 snapshots at least a day apart
|
|
ceph fs snap-schedule retention remove / h 24 # remove retention for 24 hourlies
|
|
ceph fs snap-schedule retention add / 24h4w # add 24 hourly and 4 weekly to retention
|
|
ceph fs snap-schedule retention remove / 7d4w # remove 7 daily and 4 weekly, leaves 24 hourly
|
|
|
|
.. note: When adding a path to snap-schedule, remember to strip off the mount
|
|
point path prefix. Paths to snap-schedule should start at the appropriate
|
|
CephFS file system root and not at the host file system root.
|
|
e.g. if the Ceph File System is mounted at ``/mnt`` and the path under which
|
|
snapshots need to be taken is ``/mnt/some/path`` then the acutal path required
|
|
by snap-schedule is only ``/some/path``.
|
|
|
|
.. note: It should be noted that the "created" field in the snap-schedule status
|
|
command output is the timestamp at which the schedule was created. The "created"
|
|
timestamp has nothing to do with the creation of actual snapshots. The actual
|
|
snapshot creation is accounted for in the "created_count" field, which is a
|
|
cumulative count of the total number of snapshots created so far.
|
|
|
|
.. note: The maximum number of snapshots to retain per directory is limited by the
|
|
config tunable `mds_max_snaps_per_dir`. This tunable defaults to 100.
|
|
To ensure a new snapshot can be created, one snapshot less than this will be
|
|
retained. So by default, a maximum of 99 snapshots will be retained.
|
|
|
|
.. note: The --fs argument is now required if there is more than one file system.
|
|
|
|
Active and inactive schedules
|
|
-----------------------------
|
|
Snapshot schedules can be added for a path that doesn't exist yet in the
|
|
directory tree. Similarly a path can be removed without affecting any snapshot
|
|
schedules on that path.
|
|
If a directory is not present when a snapshot is scheduled to be taken, the
|
|
schedule will be set to inactive and will be excluded from scheduling until
|
|
it is activated again.
|
|
A schedule can manually be set to inactive to pause the creating of scheduled
|
|
snapshots.
|
|
The module provides the `activate` and `deactivate` subcommands for this
|
|
purpose.
|
|
|
|
Examples::
|
|
|
|
ceph fs snap-schedule activate / # activate all schedules on the root directory
|
|
ceph fs snap-schedule deactivate / 1d # deactivates daily snapshots on the root directory
|
|
|
|
Limitations
|
|
-----------
|
|
Snapshots are scheduled using python Timers. Under normal circumstances
|
|
specifying 1h as the schedule will result in snapshots 1 hour apart fairly
|
|
precisely. If the mgr daemon is under heavy load however, the Timer threads
|
|
might not get scheduled right away, resulting in a slightly delayed snapshot. If
|
|
this happens, the next snapshot will be schedule as if the previous one was not
|
|
delayed, i.e. one or more delayed snapshots will not cause drift in the overall
|
|
schedule.
|
|
|
|
In order to somewhat limit the overall number of snapshots in a file system, the
|
|
module will only keep a maximum of 50 snapshots per directory. If the retention
|
|
policy results in more then 50 retained snapshots, the retention list will be
|
|
shortened to the newest 50 snapshots.
|
|
|
|
Data storage
|
|
------------
|
|
The snapshot schedule data is stored in a rados object in the cephfs metadata
|
|
pool. At runtime all data lives in a sqlite database that is serialized and
|
|
stored as a rados object.
|