ldm.md

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1	Local Disk Manager

Local Disk Manager

Local Disk Manager (LDM) is one of the modules of HwameiStor. LDM is used to simplify the management of disks on nodes. It can abstract the disk on a node into a resource for monitoring and management purposes. It's a daemon that will be deployed on each node, then detect the disk on the node, abstract it into local disk (LD) resources and save it to kubernetes.

At present, the LDM project is still in the alpha stage.

Concepts

LocalDisk (LD): LDM abstracts disk resources into objects in kubernetes. An LD resource object represents the disk resources on the host.

LocalDiskClaim (LDC): This is a way to use disks. A user can add the disk description to select a disk for use.

At present, LDC supports the following options to describe disk:

• NodeName
• Capacity
• DiskType (such as HDD/SSD/NVMe)

Usage

1. Get the LocalDisk information.

   kubectl get localdisk
   NAME               NODEMATCH        PHASE
   10-6-118-11-sda    10-6-118-11      Available
   10-6-118-11-sdb    10-6-118-11      Available

   Get locally discovered disk resource information with three columns displayed.

   • NAME: represents how this disk is displayed in the cluster resources.
   • NODEMATCH: indicates which host this disk is on.
   • PHASE: represents the current state of the disk.

   Use kubectl get localdisk <name> -o yaml to view more information about disks.

2. Claim available disks.

   1. Apply a LocalDiskClaim.

      cat << EOF | kubectl apply -f -
      apiVersion: hwameistor.io/v1alpha1
      kind: LocalDiskClaim
      metadata:
        name: <localDiskClaimName>
      spec:
        description:
          # e.g. HDD,SSD,NVMe
          diskType: <diskType>
        # the node where disks attached
        nodeName: <nodeName>
        # the owner of the allocated disks e.g. local-storage,local-disk-manager
        owner: <ownerName>
      EOF

      Allocate available disks by issuing a disk usage request. In the request description, you can add more requirements about the disk, such as disk type and capacity.

   2. Get the LocalDiskClaim information.

      kubectl get localdiskclaim <name>

   3. Once the LDC is processed successfully, it will be cleanup by the system automatically. The result will be recorded in the LocalStorageNode if the owner is local-storage.