Managed disks, external volumes, and array LUNs
View the information that is shown about managed disks or disk drives, external volumes, and array LUNs in block storage systems.
To view information about the managed disks, external volumes, or array LUNs that are associated with a storage system, click Managed Disks, External Volumes, or Array LUNs. The type of the storage system determines which of these components can be viewed.
A managed disk is storage that is virtualized by a storage virtualizer. A managed disk can represent a volume that is assigned from a back-end storage system. The disk can also represent one or more physical disks that are installed locally in a storage virtualizer. One or more managed disks can be added to a pool or managed disk group, from which volumes are allocated and assigned to host servers.
Important: Managed disks are displayed only when you view the details of the following
storage systems:
- Storage systems that run IBM Storage Virtualize
- Hitachi VSP as External Volumes
- NetApp storage systems that run ONTAP 9 as Array LUNs
The following information is shown for each
managed disk:
- Acknowledged
- Shows whether a user marked the status of a managed disk as acknowledged. An acknowledged status indicates that the status was reviewed and is either resolved or can be ignored. An acknowledged status is not used when the status of related, higher-level resources is determined.
- Available Capacity (GiB)
- The storage capacity that is available (not allocated) on a managed disk.
- Back-end Storage System
- The name of the storage system that is providing storage to a managed disk.
- Capacity (GiB)
- (Previously known as Total Capacity) Total amount of storage space on a managed disk.
- Class
- The technology type of the managed disk, such as Tier 0 and Tier 1 flash solid-state drives (SSDs), NVMe SSDs, Storage Class Memory, Enterprise and Nearline hard disk drives (HDDs), and other types. Managed disks that consist of internal, local disks are classified automatically by the cluster, but you must manually classify managed disks that consist of external disks.
- Drive Compression Ratio
- The ratio of the uncompressed data size to the compressed data size for a particular managed disk in a storage system.
- Drive Compression Savings (%)
- The estimated amount and percentage of capacity that is saved in a particular managed disk in a storage system.
- Easy Tier
- The tier that a managed disk is assigned to by the internal cluster auto-detection for internal disks or by the user for external disks. This classification is used by the storage virtualizer to determine when to activate the Easy Tier function for certain pools.
- Easy Tier® Load
- The workload size of a managed disk. Easy Tier uses this value to identify the IOPS capability of the associated storage tier. Possible values are low, medium, high, and very high. You can use this value to fine-tune the utilization of backend storage and troubleshoot performance issues, such as determining if the setting is incorrect for a managed disk.
- Mode
-
The allocation mode of the managed disk. The following allocation modes might be shown:
- Unmanaged
- The external volume is virtualized as a managed disk, but is not being used.
- Managed
- The external volume is virtualized as a managed disk and is assigned to a pool or a managed disk group.
- Image
- The external volume is not virtualized, which means that the associated volume provides a direct block-for-block translation of the external volume.
- Array
- One or more internal or local disks are used to form the managed disk.
- Pool
- The name of the storage pool or managed disk group to which a managed disk belongs. If a managed disk is associated with a primordial pool, or is not yet assigned to a pool, then it is unmanaged. The value None is displayed.
- Pool Compression Ratio
- The ratio of the uncompressed data size to the compressed data size for the pool that contains the managed disk.
- Pool Compression Savings
- The estimated amount and percentage of capacity that is saved in the pool that contains the managed disk.
- Quorum disk
- A quorum disk is an MDisk that is used exclusively for system management. A storage system might have only one active quorum disk.
- RAID Level
- The RAID level of a managed disk, such as RAID 5 and RAID 10, or if the managed disk is a distributed RAID array, the RAID level is prefixed with “D”, such as DRAID 5. The RAID level affects the performance and fault tolerance of the volumes that are used by a managed disk. This value is shown only when the managed disk is a RAID array that was built from internal, local disks in the storage virtualizer. The value None indicates that a managed disk is a single, local disk and performance or fault tolerance is not improved.
- Status
- The status of a managed disk. Use the status to determine the condition of a managed disk, and if any actions must be taken. For example, if a managed disk has an Error status, take immediate action to correct the problem.
- Storage System
- The name of the storage virtualizer that contains a managed disk. A storage virtualizer is a storage system that virtualizes storage space from internal storage or from another storage system, such as a SAN Volume Controller or Storwize V7000.
- Total Compression Ratio
- The ratio of the uncompressed data size to the compressed data size for all the managed disks in a storage system.
- Total Compression Savings
- The estimated amount and percentage of capacity that is saved in all managed disks in a particular storage system by using data compression techniques.
- Volumes
- The number of volumes that are partially or completely on a managed disk.