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LVMd

LVMd is a gRPC service to manage LVM volumes. It is composed of two services:

  • VGService
    • Provide volume group information: list logical volume, list and watch free bytes
  • LVService
    • Provide management of logical volumes: create, remove, resize

Command-line Flags

Option Type Default value Description
config string /etc/topolvm/lvmd.yaml Config file path for device-class settings
container - not set Set if LVMd runs in the container

Config File Format

socket-name: /run/topolvm/lvmd.sock
device-classes:
  - name: ssd
    volume-group: ssd-vg
    spare-gb: 10
    default: true
  - name: hdd
    volume-group: hdd-vg
    spare-gb: 10
  - name: striped
    volume-group: multi-pv-vg
    spare-gb: 10
    stripe: 2
    stripe-size: "64"
  - name: raid
    volume-group: raid-vg
    lvcreate-options:
      - --type=raid1
Name Type Default Description
socket-name string /run/topolvm/lvmd.sock Unix domain socket endpoint of gRPC
device-classes map[string]DeviceClass - The device-class settings

The device-class settings can be specified in the following fields:

Name Type Default Description
name string - The name of a device-class.
volume-group string - The group where this device-class creates the logical volumes.
spare-gb uint64 10 Storage capacity in GiB to be spared.
default bool false A flag to indicate that this device-class is used by default.
stripe uint - The number of stripes in the logical volume.
stripe-size string - The amount of data that is written to one device before moving to the next device.
lvcreate-options []string - Extra arguments to pass to lvcreate, e.g. ["--type=raid1"].

Note

Striping can be configured both using the dedicated options (stripe and stripe-size) and lvcreate-options. Either one can be used but not together since this would lead to duplicate arguments to lvcreate. This means that you should never set lvcreate-options: ["--stripes=n"] and stripe: n at the same time. It is fine to use both as long as lvcreate-options are not used for striping:

stripe: 2
lvcreate-options: ["--mirrors=1"]

Note

After changing the configuration file, you need to restart LVMd to reflect this change. If LVMd is deployed as a DaemonSet, pod restart is needed after changing the corresponding ConfigMap. If you want to restart LVMd automatically after changing configuration, please use 3rd party tools like Reloader.

Spare Capacity

LVMd subtracts a certain amount from the free space of a volume group before reporting the free space of the volume group.

The default spare capacity is 10 GiB. This can be changed with --spare command-line flag.

API Specification

See here.