Drives are added to DirectPV to provision volumes. This involves a two step process as shown below.
discover command.
The discover command probes eligible drives from DirectPV nodes and stores drive information in a YAML file. You should carefully examine the YAML file and set the select field to yes or no value to indicate drive selection. select field is set to yes value by default. Below is an example of the discover command:# Probe and save drive information to drives.yaml file.
$ kubectl directpv discover
Discovered node 'master' ✔
Discovered node 'node1' ✔
┌─────────────────────┬────────┬───────┬─────────┬────────────┬──────┬───────────┬─────────────┐
│ ID │ NODE │ DRIVE │ SIZE │ FILESYSTEM │ MAKE │ AVAILABLE │ DESCRIPTION │
├─────────────────────┼────────┼───────┼─────────┼────────────┼──────┼───────────┼─────────────┤
│ 252:16$ud8mwCjPT... │ master │ vdb │ 512 MiB │ - │ - │ YES │ - │
│ 252:16$gGz4UIuBj... │ node1 │ vdb │ 512 MiB │ - │ - │ YES │ - │
└─────────────────────┴────────┴───────┴─────────┴────────────┴──────┴───────────┴─────────────┘
Generated 'drives.yaml' successfully.
# Show generated drives.yaml file.
$ cat drives.yaml
version: v1
nodes:
- name: master
drives:
- id: 252:16$ud8mwCjPTH8147TysmiQ2GGLpffqUht6bz7NtHqReJo=
name: vdb
size: 536870912
make: ""
select: "yes"
- name: node1
drives:
- id: 252:16$gGz4UIuBjQlO1KibOv7bZ+kEDk3UCeBneN/UJdqdQl4=
name: vdb
size: 536870912
make: ""
select: "yes"
init command.
The init command creates a request to add the selected drives in the YAML file generated using the discover command. As this process wipes out all data on the selected drives, wrong drive selection will lead to permanent data loss. Below is an example of init command:$ kubectl directpv init drives.yaml
███████████████████████████████████████████████████████████████████████████ 100%
Processed initialization request 'c24e22f5-d582-49ba-a883-2ce56909904e' for node 'master' ✔
Processed initialization request '7e38a453-88ed-412c-b146-03eef37b23bf' for node 'node1' ✔
┌──────────────────────────────────────┬────────┬───────┬─────────┐
│ REQUEST_ID │ NODE │ DRIVE │ MESSAGE │
├──────────────────────────────────────┼────────┼───────┼─────────┤
│ c24e22f5-d582-49ba-a883-2ce56909904e │ master │ vdb │ Success │
│ 7e38a453-88ed-412c-b146-03eef37b23bf │ node1 │ vdb │ Success │
└──────────────────────────────────────┴────────┴───────┴─────────┘
Refer to the discover command and the init command for more information.
To get information of drives from DirectPV, run the list drives command. Below is an example:
$ kubectl directpv list drives
┌────────┬──────┬──────┬─────────┬─────────┬─────────┬────────┐
│ NODE │ NAME │ MAKE │ SIZE │ FREE │ VOLUMES │ STATUS │
├────────┼──────┼──────┼─────────┼─────────┼─────────┼────────┤
│ master │ vdb │ - │ 512 MiB │ 506 MiB │ - │ Ready │
│ node1 │ vdb │ - │ 512 MiB │ 506 MiB │ - │ Ready │
└────────┴──────┴──────┴─────────┴─────────┴─────────┴────────┘
Refer to the list drives command for more information.
Drives are labeled to set custom tagging which can be used in volume provisioning. Below is an example:
# Set label 'tier' key to 'hot' value.
$ kubectl directpv label drives tier=hot
# Remove label 'tier'.
$ kubectl directpv label drives tier-
Refer to the label drives command for more information.
Replace a faulty drive with a new drive on a same node. In this process, all volumes in the faulty drive are moved to the new drive then faulty drive is removed from DirectPV. Currently, DirectPV does not support moving data on the volume to the new drive. Use replace.sh script to perform drive replacement. Below is an example:
# Replace 'sdd' drive by 'sdf' drive on 'node1' node
$ replace.sh sdd sdf node1
Drives that do not contain any volumes can be removed. Below is an example:
# Remove drive 'vdb' from 'node1' node
$ kubectl directpv remove --drives=vdb --nodes=node1
Refer remove command for more information.
CAUTION: THIS IS DANGEROUS OPERATION WHICH LEADS TO DATA LOSS
By Kubernetes design, StatefulSet workload is active only if all of its pods are in running state. Any faulty drive(s) will prevent the statefulset from starting up. DirectPV provides a workaround to suspend failed drives which will mount the respective volumes on empty /var/lib/directpv/tmp directory with read-only access. This can be done by executing the suspend drives command. Below is an example:
$ kubectl directpv suspend drives af3b8b4c-73b4-4a74-84b7-1ec30492a6f0
Suspended drives can be resumed once they are fixed. Upon resuming, the corresponding volumes will resume using the respective allocated drives. This can be done by using the resume drives command. Below is an example:
$ kubectl directpv resume drives af3b8b4c-73b4-4a74-84b7-1ec30492a6f0
CAUTION: THIS IS DANGEROUS OPERATION WHICH LEADS TO DATA LOSS
In a rare situation, filesystem on faulty drives can be repaired to make them usable. As a first step, faulty drives must be suspended, then the repair command should be run for them. The repair command creates onetime Kubernetes Job with the pod name as repair-<DRIVE-ID> and these jobs are auto removed after five minutes of its completion. Progress and status of the drive repair can be viewed using kubectl log command. Below is an example:
# Suspend faulty drives
$ kubectl directpv suspend drives af3b8b4c-73b4-4a74-84b7-1ec30492a6f0
# Restart volume consumer pods and make sure associated volumes are unbound
# Run repair command on suspended drives
$ kubectl directpv repair af3b8b4c-73b4-4a74-84b7-1ec30492a6f0