Using Ceph administration socket

Use the administration socket to interact with a given daemon directly by using a UNIX socket file.

For example, the socket enables you to:

List the Ceph configuration at runtime
Set configuration values at runtime directly without relying on Monitors. This is useful when Monitors are down.
Dump historic operations
Dump the operation priority queue state
Dump operations without rebooting
Dump performance counters

In addition, using the socket is helpful when troubleshooting problems related to Ceph Monitors or OSDs.

Regardless, if the daemon is not running, a following error is returned when attempting to use the administration socket:

Error 111: Connection Refused

Important: The administration socket is only available while a daemon is running. When you shut down the daemon properly, the administration socket is removed. However, if the daemon terminates unexpectedly, the administration socket might persist.

Prerequisites

A running IBM Storage Ceph cluster.
Root-level access to the node.

Procedure

Log into the cephadm shell:

Example
```
[root@host01 ~]# cephadm shell
```

To use the socket:

Syntax

ceph daemon MONITOR_ID COMMAND

Replace:

MONITOR_ID of the daemon

COMMAND with the command to run. Use help to list the available commands for a given daemon.

To view the status of a Ceph Monitor:

Example

[ceph: root@host01 /]# ceph daemon mon.host01 help
{
    "add_bootstrap_peer_hint": "add peer address as potential bootstrap peer for cluster bringup",
    "add_bootstrap_peer_hintv": "add peer address vector as potential bootstrap peer for cluster bringup",
    "compact": "cause compaction of monitor's leveldb/rocksdb storage",
    "config diff": "dump diff of current config and default config",
    "config diff get": "dump diff get <field>: dump diff of current and default config setting <field>",
    "config get": "config get <field>: get the config value",
    "config help": "get config setting schema and descriptions",
    "config set": "config set <field> <val> [<val> ...]: set a config variable",
    "config show": "dump current config settings",
    "config unset": "config unset <field>: unset a config variable",
    "connection scores dump": "show the scores used in connectivity-based elections",
    "connection scores reset": "reset the scores used in connectivity-based elections",
    "counter dump": "dump all labeled and non-labeled counters and their values",
    "counter schema": "dump all labeled and non-labeled counters schemas",
    "dump_historic_ops": "show recent ops",
    "dump_historic_slow_ops": "show recent slow ops",
    "dump_mempools": "get mempool stats",
    "get_command_descriptions": "list available commands",
    "git_version": "get git sha1",
    "heap": "show heap usage info (available only if compiled with tcmalloc)",
    "help": "list available commands",
    "injectargs": "inject configuration arguments into running daemon",
    "log dump": "dump recent log entries to log file",
    "log flush": "flush log entries to log file",
    "log reopen": "reopen log file",
    "mon_status": "report status of monitors",
    "ops": "show the ops currently in flight",
    "perf dump": "dump non-labeled counters and their values",
    "perf histogram dump": "dump perf histogram values",
    "perf histogram schema": "dump perf histogram schema",
    "perf reset": "perf reset <name>: perf reset all or one perfcounter name",
    "perf schema": "dump non-labeled counters schemas",
    "quorum enter": "force monitor back into quorum",
    "quorum exit": "force monitor out of the quorum",
    "sessions": "list existing sessions",
    "smart": "Query health metrics for underlying device",
    "sync_force": "force sync of and clear monitor store",
    "version": "get ceph version"
}

Example

[ceph: root@host01 /]# ceph daemon mon.host01 mon_status

{
    "name": "host01",
    "rank": 0,
    "state": "leader",
    "election_epoch": 120,
    "quorum": [
        0,
        1,
        2
    ],
    "quorum_age": 206358,
    "features": {
        "required_con": "2449958747317026820",
        "required_mon": [
            "kraken",
            "luminous",
            "mimic",
            "osdmap-prune",
            "nautilus",
            "octopus",
            "pacific",
            "elector-pinging"
        ],
        "quorum_con": "4540138297136906239",
        "quorum_mon": [
            "kraken",
            "luminous",
            "mimic",
            "osdmap-prune",
            "nautilus",
            "octopus",
            "pacific",
            "elector-pinging"
        ]
    },
    "outside_quorum": [],
    "extra_probe_peers": [],
    "sync_provider": [],
    "monmap": {
        "epoch": 3,
        "fsid": "81a4597a-b711-11eb-8cb8-001a4a000740",
        "modified": "2021-05-18T05:50:17.782128Z",
        "created": "2021-05-17T13:13:13.383313Z",
        "min_mon_release": 16,
        "min_mon_release_name": "pacific",
        "election_strategy": 1,
        "disallowed_leaders: ": "",
        "stretch_mode": false,
        "features": {
            "persistent": [
                "kraken",
                "luminous",
                "mimic",
                "osdmap-prune",
                "nautilus",
                "octopus",
                "pacific",
                "elector-pinging"
            ],
            "optional": []
        },
        "mons": [
            {
                "rank": 0,
                "name": "host01",
                "public_addrs": {
                    "addrvec": [
                        {
                            "type": "v2",
                            "addr": "10.74.249.41:3300",
                            "nonce": 0
                        },
                        {
                            "type": "v1",
                            "addr": "10.74.249.41:6789",
                            "nonce": 0
                        }
                    ]
                },
                "addr": "10.74.249.41:6789/0",
                "public_addr": "10.74.249.41:6789/0",
                "priority": 0,
                "weight": 0,
                "crush_location": "{}"
            },
            {
                "rank": 1,
                "name": "host02",
                "public_addrs": {
                    "addrvec": [
                        {
                            "type": "v2",
                            "addr": "10.74.249.55:3300",
                            "nonce": 0
                        },
                        {
                            "type": "v1",
                            "addr": "10.74.249.55:6789",
                            "nonce": 0
                        }
                    ]
                },
                "addr": "10.74.249.55:6789/0",
                "public_addr": "10.74.249.55:6789/0",
                "priority": 0,
                "weight": 0,
                "crush_location": "{}"
            },
            {
                "rank": 2,
                "name": "host03",
                "public_addrs": {
                    "addrvec": [
                        {
                            "type": "v2",
                            "addr": "10.74.249.49:3300",
                            "nonce": 0
                        },
                        {
                            "type": "v1",
                            "addr": "10.74.249.49:6789",
                            "nonce": 0
                        }
                    ]
                },
                "addr": "10.74.249.49:6789/0",
                "public_addr": "10.74.249.49:6789/0",
                "priority": 0,
                "weight": 0,
                "crush_location": "{}"
            }
        ]
    },
    "feature_map": {
        "mon": [
            {
                "features": "0x3f01cfb9fffdffff",
                "release": "luminous",
                "num": 1
            }
        ],
        "osd": [
            {
                "features": "0x3f01cfb9fffdffff",
                "release": "luminous",
                "num": 3
            }
        ]
    },
    "stretch_mode": false
}

Alternatively, specify the Ceph daemon by using its socket file:

Syntax
```
ceph daemon /var/run/ceph/SOCKET_FILE COMMAND
```

To view the status of a Ceph OSD named osd.0 on the specific host:

Example

[ceph: root@host01 /]# ceph daemon /var/run/ceph/ceph-osd.0.asok status
{
    "cluster_fsid": "9029b252-1668-11ee-9399-001a4a000429",
    "osd_fsid": "1de9b064-b7a5-4c54-9395-02ccda637d21",
    "whoami": 0,
    "state": "active",
    "oldest_map": 1,
    "newest_map": 58,
    "num_pgs": 33
}

Note: You can use help instead of status for the various options that are available for the specific daemon.

List all socket files for the Ceph processes:

Example
```
[ceph: root@host01 /]# ls /var/run/ceph
```

Reference

For more information, see Identifying problems.