Scale down nodes
Removing offline nodes
This document describes how to remove an offline node from a cluster. If you are specifically interested in decommissioning nodes with no storage that have been offline for an extended period, see Automatic decommission of storageless nodes.
Identify the cluster that needs to be managed:
pxctl statusStatus: PX is operational Node ID: a56a4821-6f17-474d-b2c0-3e2b01cd0bc3 IP: 147.75.198.197 Local Storage Pool: 2 pools Pool IO_Priority Size Used Status Zone Region 0 LOW 200 GiB 1.0 GiB Online default default 1 LOW 120 GiB 1.0 GiB Online default default Local Storage Devices: 2 devices Device Path Media Type SizLast-Scan 0:1 /dev/mapper/volume-27dbb728 STORAGE_MEDIUM_SSD 200 GiB 08 Jan 17 05:39 UTC 1:1 /dev/mapper/volume-0a31ef46 STORAGE_MEDIUM_SSD 120 GiB 08 Jan 17 05:39 UTC total - 320 GiB Cluster Summary Cluster ID: bb4bcf13-d394-11e6-afae-0242ac110002 Node IP: 147.75.198.197 - Capacity: 2.0 GiB/320 GiB Online (This node) Node IP: 10.99.117.129 - Capacity: 1.2 GiB/100 GiB Online Node IP: 10.99.119.1 - Capacity: 1.2 GiB/100 GiB Online Global Storage Pool Total Used : 4.3 GiB Total Capacity : 520 GiBList the nodes in the cluster:
pxctl cluster listCluster ID: bb4bcf13-d394-11e6-afae-0242ac110002 Status: OK Nodes in the cluster: ID DATA IP CPU MEM TOTAL MEM FREE CONTAINERS VERSION STATUS a56a4821-6f17-474d-b2c0-3e2b01cd0bc3 147.75.198.197 1.629073 8.4 GB 7.9 GB N/A 1.1.2-c27cf42 Online 2c7d4e55-0c2a-4842-8594-dd5084dce208 10.99.117.129 0.125156 8.4 GB 8.0 GB N/A 1.1.3-b33d4fa Online 5de71f19-8ac6-443c-bd83-d3478c485a61 10.99.119.1 0.25 8.4 GB 8.0 GB N/A 1.1.3-b33d4fa OnlineList the volumes in the cluster:
pxctl volume listID NAME SIZE HA SHARED ENCRYPTED PRIORITSTATUS 845707146523643463 testvol 1 GiB 1 no no LOW up - attached on 147.75.198.197In this case, there is one volume in the cluster and it is attached to node with IP 147.75.198.97
Identify the node that you want to remove from the cluster.
In the following example, node 147.75.198.197 has been marked as offline:
pxctl cluster listCluster ID: bb4bcf13-d394-11e6-afae-0242ac110002 Status: OK Nodes in the cluster: ID DATA IP CPU MEM TOTAL MEM FREE CONTAINERS VERSION STATUS 2c7d4e55-0c2a-4842-8594-dd5084dce208 10.99.117.129 5.506884 8.4 GB 8.0 GB N/A 1.1.3-b33d4fa Online 5de71f19-8ac6-443c-bd83-d3478c485a61 10.99.119.1 0.25 8.4 GB 8.0 GB N/A 1.1.3-b33d4fa Online a56a4821-6f17-474d-b2c0-3e2b01cd0bc3 147.75.198.197 - - N/A 1.1.2-c27cf42 OfflineAttach and detach the volume in one of the surviving nodes:
pxctl host attach 845707146523643463Volume successfully attached at: /dev/pxd/pxd845707146523643463pxctl host detach 845707146523643463Volume successfully detachedDelete the local volume that belonged to the offline node:
pxctl volume delete 845707146523643463Volume 845707146523643463 successfully deleted.Delete the node that is offline:
pxctl cluster delete a56a4821-6f17-474d-b2c0-3e2b01cd0bc3Node a56a4821-6f17-474d-b2c0-3e2b01cd0bc3 successfully deleted.List the nodes in the cluster to make sure that the node is removed:
pxctl cluster listCluster ID: bb4bcf13-d394-11e6-afae-0242ac110002 Status: OK Nodes in the cluster: ID DATA IP CPU MEM TOTAL MEM FREE CONTAINERS VERSION STATUS 2c7d4e55-0c2a-4842-8594-dd5084dce208 10.99.117.129 4.511278 8.4 GB 8.0 GB N/A 1.1.3-b33d4fa Online 5de71f19-8ac6-443c-bd83-d3478c485a61 10.99.119.1 0.500626 8.4 GB 8.0 GB N/A 1.1.3-b33d4fa OnlineShow the cluster status:
pxctl statusStatus: PX is operational Node ID: 2c7d4e55-0c2a-4842-8594-dd5084dce208 IP: 147.75.198.199 Local Storage Pool: 1 pool Pool IO_Priority Size Used Status Zone Region 0 LOW 100 GiB 1.2 GiB Online default default Local Storage Devices: 1 device Device Path Media Type Size Last-Scan 0:1 /dev/mapper/volume-9f6be49c STORAGE_MEDIUM_SSD 100 GiB08 Jan 17 06:34 UTC total - 100 GiB Cluster Summary Cluster ID: bb4bcf13-d394-11e6-afae-0242ac110002 Node IP: 10.99.117.129 - Capacity: 1.2 GiB/100 GiB Online (This node) Node IP: 10.99.119.1 - Capacity: 1.2 GiB/100 GiB Online Global Storage Pool Total Used : 2.3 GiB Total Capacity : 200 GiB
Removing a functional node from a cluster
A functional Portworx node may need to be removed from the cluster. In this section, we’ll demonstrate the removal of a node by running commands on the node itself as well as the removal of a node from another node.
The following output shows the state of the cluster and the different node IPs and node IDs:
pxctl statusStatus: PX is operational
Node ID: 5f8b8417-af2b-4ea7-930e-0027f6bbcbd1
IP: 192.0.2.0
Local Storage Pool: 1 pool
POOL IO_PRIORITY SIZE USED STATUS ZONE REGION
0 LOW 64 GiB 11 GiB Online c us-east-1
Local Storage Devices: 1 device
Device Path Media Type Size Last-Scan
0:1 /dev/xvdf STORAGE_MEDIUM_SSD 64 GiB 25 Feb 17 21:13 UTC
total - 64 GiB
Cluster Summary
Cluster ID: 0799207a-eec6-4fc6-a5f1-d4a612b74cc3
IP ID Used Capacity Status
172.31.40.38 ec3ed4b9-68d5-4e83-a7ce-2bc112f5f131 11 GiB 64 GiB Online
172.31.37.211 17a6fb2c-0d19-4bae-a73f-a85e0514ae8b 11 GiB 64 GiB Online
172.31.35.130 a91175b6-ff69-4eff-8b7f-893373631483 11 GiB 64 GiB Online
172.31.45.106 048cc2f8-022e-47d9-b600-2eeddcd64d51 11 GiB 64 GiB Online
172.31.45.56 f9cb673e-adfa-4e4f-a99a-ec8e1420e645 11 GiB 64 GiB Online
172.31.46.119 5f8b8417-af2b-4ea7-930e-0027f6bbcbd1 11 GiB 64 GiB Online (This node)
172.31.39.201 355ee6aa-c7eb-4ac6-b16b-936b1b58aa24 11 GiB 64 GiB Online
172.31.33.151 871c503d-fa6e-4599-a533-41e70a72eafd 11 GiB 64 GiB Online
172.31.33.252 651ca0f4-c156-4a14-b2f3-428e727eb6b8 11 GiB 64 GiB Online
Global Storage Pool
Total Used : 99 GiB
Total Capacity : 576 GiBSuspend active cloudsnap operations
Identify any active cloudsnap operations being run on the node that you intend to decommission:
pxctl cloudsnap statusThe
STATEof active operations shows asBackup-Active:NAME SOURCEVOLUME STATE NODE TIME-ELAPSED COMPLETED 0ddf4424-c7a7-4435-a80d-278535e49860 885345022234521857 Backup-Done 10.13.90.125 39.746191264s Tue, 22 Mar 2022 22:53:37 UTC 31ab4e56-f0d2-4bdf-a236-3c3ccf47f276 186701534582547510 Backup-Done 10.13.90.122 1.677455484s Tue, 22 Mar 2022 23:59:49 UTC 274c0d4c-12a4-403f-8b0b-73176c2d03e2 885345022234521857 Backup-Done 10.13.90.125 27.550329395s Wed, 23 Mar 2022 00:00:15 UTC ee91a94e-b311-4c4d-ba02-2307865c1b93 649554470078043771 Backup-Active 10.13.90.125 5m12.61653365sFrom this output, identify the volumes with active backups. For example, if node 10.13.90.125 is being decommissioned, then the volume with active backup is
649554470078043771.Identify the namespace of the volume the cloudsnap operation is occuring on. The namespace is displayed under the
Labelssection in the output from the following command. Replace<source_volume>with theSOURCEVOLUMEvalue for the volume that is in aBackup-Activestate from the previous output:pxctl volume inspect <source_volume>Volume : 649554470078043771 Name : pvc-d509932e-7772-4ac5-9bc0-d4827680f6de Size : 500 GiB Format : ext4 HA : 3 IO Priority : LOW Creation time : Mar 22 20:37:52 UTC 2022 Shared : v4 (service) Status : up State : Attached: 78dbf17e-28b1-4c78-b35b-10f4e076cac8 (10.13.90.119) Last Attached : Mar 22 20:37:58 UTC 2022 Device Path : /dev/pxd/pxd649554470078043771 Labels : mount_options=nodiscard=true,namespace=vdbench,nodiscard=true,pvc=vdbench-pvc-sharedv4,repl=3,sharedv4=true,sharedv4_svc_type=ClusterIP ...Suspend backup operations for the volume and wait for current backup to complete:
storkctl suspend volumesnapshotschedule vdbench-pvc-sharedv4-schedule -n vdbenchVerify the suspension. The
SUSPENDfield will show astrue:storkctl get volumesnapshotschedule -n vdbenchNAME PVC POLICYNAME PRE-EXEC-RULE POST-EXEC-RULE RECLAIM-POLICY SUSPEND LAST-SUCCESS-TIME vdbench-pvc-sharedv4-schedule vdbench-pvc-sharedv4 testpolicy Delete true 22 Mar 22 17:10 PDT
Repeat these steps until all active snaps complete and all backup operations are suspended on the node that you want to decommission.
Prevention of data loss
If any node hosts a volume with replication factor of 1, then Portworx disallows decommissioning of such nodes because there is data loss.
One possible workaround to decommission such a node is to increase the replication of single replica volumes by running volume ha-update.
List all the volumes hosts on the decommisioning node:
pxctl volumev list --node 048cc2f8-022e-47d9-b600-2eeddcd64d51ID NAME SIZE HA SHARED ENCRYPTED PROXY-VOLUME IO_PRIORITY STATUS SNAP-ENABLED 633738568577538909 pvc-d509932e-7772-4ac5-9bc0-d4827680f6de 2 GiB 3 no no no LOW up - attached on 172.31.45.106 no 161898313715947409 pvc-2d114856-2df4-47e9-b2af-68f0d970e10c 2 GiB 1 no no no LOW up - attached on 172.31.45.106 noIncrease the replication factor:
pxctl volume ha-update --repl 2 161898313715947409
Once the volume is completely replicated onto another node, continue with the node decommissioning. This time, the volume already has another replica on another node, so decommissioning the node will reduce the replication factor of the volume and remove the node.
Placing the node in maintenance mode
After identifying the node to be removed (see “Identify the node that you want to remove from the cluster” above), place the node in maintenance mode.
Log in to the node to be decommissioned:
pxctl service maintenance --enterThis is a disruptive operation, PX will restart in maintenance mode.
Are you sure you want to proceed ? (Y/N): y
Entered maintenance mode.Run the cluster delete command
Example 1: Running the cluster delete command from a different node
ssh to 172.31.46.119 and run the following command:
pxctl cluster delete 048cc2f8-022e-47d9-b600-2eeddcd64d51Node 048cc2f8-022e-47d9-b600-2eeddcd64d51 successfully deleted.Example 2: Running the cluster delete command from the same node
ssh to 172.31.33.252 and type:
pxctl cluster delete 651ca0f4-c156-4a14-b2f3-428e727eb6b8Node 651ca0f4-c156-4a14-b2f3-428e727eb6b8 successfully deleted.Clean up Portworx metadata on the node
To learn how to remove or clean up Portworx metadata on the decommmisioned node, see clean up Portworx metadata on the node.
Automatic decommission of storageless nodes
Storageless nodes that are initialized and added to the cluster may not be needed once they complete their tasks (such as in a scheduler workflow). If they are taken offline or destroyed, the cluster will still retain the nodes and mark them as offline.
If eventually a majority of such nodes exist, the cluster won’t have a quorum of nodes that are online. The solution is to run cluster delete commands and remove such nodes. This gets more laborious with more such nodes or an increased frequency of such nodes added and taken down.
To help with this, Portworx waits until a grace period of 48 hours has passed. After this period, offline nodes with no storage will be removed from the cluster. There is no CLI command needed to turn on or trigger this feature.