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Chapter 2. Understanding Process Management for Ceph
As a storage administrator, you can manipulate the Ceph daemons in various ways. Manipulating these daemons allows you to start, stop and restart all of the Ceph services as needed.
2.1. Prerequisites Link kopierenLink in die Zwischenablage kopiert!
- A running Red Hat Ceph Storage cluster.
2.2. An Overview of Process Management for Ceph Link kopierenLink in die Zwischenablage kopiert!
In Red Hat Ceph Storage 3, all process management is done through the Systemd service. Each time you want to start, restart, and stop the Ceph daemons, you must specify the daemon type or the daemon instance.
Additional Resources
- For more information about using Systemd, see Chapter 9 in the Red Hat Enterprise Linux System Administrator’s Guide.
2.3. Starting, Stopping, and Restarting All the Ceph Daemons Link kopierenLink in die Zwischenablage kopiert!
To start, stop, or restart all the running Ceph daemons on a node, follow these procedures.
Prerequisites
-
Having
rootaccess to the node.
Procedure
Starting all Ceph daemons:
[root@admin ~]# systemctl start ceph.targetStopping all Ceph daemons:
[root@admin ~]# systemctl stop ceph.targetRestarting all Ceph daemons:
[root@admin ~]# systemctl restart ceph.target
2.4. Starting, Stopping, and Restarting the Ceph Daemons by Type Link kopierenLink in die Zwischenablage kopiert!
To start, stop, or restart all Ceph daemons of a particular type, follow these procedures on the node running the Ceph daemons.
Prerequisites
-
Having
rootaccess to the node.
Procedure
On Ceph Monitor nodes:
Starting
[root@mon ~]# systemctl start ceph-mon.targetStopping
[root@mon ~]# systemctl stop ceph-mon.targetRestarting
[root@mon ~]# systemctl restart ceph-mon.targetOn Ceph Manager nodes:
Starting
[root@mgr ~]# systemctl start ceph-mgr.targetStopping
[root@mgr ~]# systemctl stop ceph-mgr.targetRestarting
[root@mgr ~]# systemctl restart ceph-mgr.targetOn Ceph OSD nodes:
Starting
[root@osd ~]# systemctl start ceph-osd.targetStopping
[root@osd ~]# systemctl stop ceph-osd.targetRestarting
[root@osd ~]# systemctl restart ceph-osd.targetOn Ceph Object Gateway nodes:
Starting
[root@rgw ~]# systemctl start ceph-radosgw.targetStopping
[root@rgw ~]# systemctl stop ceph-radosgw.targetRestarting
[root@rgw ~]# systemctl restart ceph-radosgw.target
2.5. Starting, Stopping, and Restarting a Ceph Daemons by Instance Link kopierenLink in die Zwischenablage kopiert!
To start, stop, or restart a Ceph daemon by instance, follow these procedures on the node running the Ceph daemons.
Prerequisites
-
Having
rootaccess to the node.
Procedure
On a Ceph Monitor node:
Starting
[root@mon ~]# systemctl start ceph-mon@$MONITOR_HOST_NAMEStopping
[root@mon ~]# systemctl stop ceph-mon@$MONITOR_HOST_NAMERestarting
[root@mon ~]# systemctl restart ceph-mon@$MONITOR_HOST_NAMEReplace
-
$MONITOR_HOST_NAMEwith the name of the Ceph Monitor node.
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On a Ceph Manager node:
Starting
[root@mgr ~]# systemctl start ceph-mgr@MANAGER_HOST_NAMEStopping
[root@mgr ~]# systemctl stop ceph-mgr@MANAGER_HOST_NAMERestarting
[root@mgr ~]# systemctl restart ceph-mgr@MANAGER_HOST_NAMEReplace
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$MANAGER_HOST_NAMEwith the name of the Ceph Manager node.
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On a Ceph OSD node:
Starting
[root@osd ~]# systemctl start ceph-osd@$OSD_NUMBERStopping
[root@osd ~]# systemctl stop ceph-osd@$OSD_NUMBERRestarting
[root@osd ~]# systemctl restart ceph-osd@$OSD_NUMBERReplace
$OSD_NUMBERwith theIDnumber of the Ceph OSD.For example, when looking at the
ceph osd treecommand output,osd.0has anIDof0.
On a Ceph Object Gateway node:
Starting
[root@rgw ~]# systemctl start ceph-radosgw@rgw.$OBJ_GATEWAY_HOST_NAMEStopping
[root@rgw ~]# systemctl stop ceph-radosgw@rgw.$OBJ_GATEWAY_HOST_NAMERestarting
[root@rgw ~]# systemctl restart ceph-radosgw@rgw.$OBJ_GATEWAY_HOST_NAMEReplace
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$OBJ_GATEWAY_HOST_NAMEwith the name of the Ceph Object Gateway node.
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2.6. Powering down and rebooting a Red Hat Ceph Storage cluster Link kopierenLink in die Zwischenablage kopiert!
Follow the below procedure for powering down and rebooting the Ceph cluster:
Prerequisites
-
Having
rootaccess.
Procedure
Powering down the Red Hat Ceph Storage cluster
Stop the clients from using the RBD images, NFS-Ganesha Gateway, and RADOS Gateway on this cluster and any other clients.
On the NFS-Ganesha Gateway node:
# systemctl stop nfs-ganesha.serviceOn the RADOS Gateway node:
# systemctl stop ceph-radosgw.target
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The cluster must be in healthy state (
Health_OKand all PGsactive+clean) before proceeding. Runceph statuson a node with the client keyrings, for example, the Ceph Monitor or OpenStack controller nodes, to ensure the cluster is healthy. If you use the Ceph File System (
CephFS), theCephFScluster must be brought down. Taking aCephFScluster down is done by reducing the number of ranks to1, setting thecluster_downflag, and then failing the last rank. For example:#ceph fs set <fs_name> max_mds 1 #ceph mds deactivate <fs_name>:1 # rank 2 of 2 #ceph status # wait for rank 1 to finish stopping #ceph fs set <fs_name> cluster_down true #ceph mds fail <fs_name>:0Setting the
cluster_downflag prevents standbys from taking over the failed rank.Set the
noout,norecover,norebalance,nobackfill,nodownandpauseflags. Run the following on a node with the client keyrings, for example, the Ceph Monitor or OpenStack controller node:#ceph osd set noout #ceph osd set norecover #ceph osd set norebalance #ceph osd set nobackfill #ceph osd set nodown #ceph osd set pauseShut down the OSD nodes one by one:
[root@osd ~]# systemctl stop ceph-osd.targetShut down the monitor nodes one by one:
[root@mon ~]# systemctl stop ceph-mon.target
Rebooting the Red Hat Ceph Storage cluster
Power on the monitor nodes:
[root@mon ~]# systemctl start ceph-mon.targetPower on the OSD nodes:
[root@osd ~]# systemctl start ceph-osd.target- Wait for all the nodes to come up. Verify all the services are up and the connectivity is fine between the nodes.
Unset the
noout,norecover,norebalance,nobackfill,nodownandpauseflags. Run the following on a node with the client keyrings, for example, the Ceph Monitor or OpenStack controller node:#ceph osd unset noout #ceph osd unset norecover #ceph osd unset norebalance #ceph osd unset nobackfill #ceph osd unset nodown #ceph osd unset pauseIf you use the Ceph File System (
CephFS), theCephFScluster must be brought back up by setting thecluster_downflag tofalse:[root@admin~]# ceph fs set <fs_name> cluster_down falseStart the RADOS Gateway and NFS-Ganesha Gateway.
On the RADOS Gateway node:
# systemctl start ceph-radosgw.targetOn the NFS-Ganesha Gateway node:
# systemctl start nfs-ganesha.service
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Verify the cluster is in healthy state (
Health_OKand all PGsactive+clean). Runceph statuson a node with the client keyrings, for example, the Ceph Monitor or OpenStack controller nodes, to ensure the cluster is healthy.
2.7. Additional Resources Link kopierenLink in die Zwischenablage kopiert!
For more information about installing Red Hat Ceph Storage, see:
- Installation Guide for Red Hat Enterprise Linux
- Installation Guide for Ubuntu