Capacity metrics for block storage systems

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To review trends in capacity and space usage for storage, you add metrics to capacity charts. You use the charts to detect capacity shortages and space usage trends.

Alphabetical lists of the capacity and space usage metrics that you can add to charts are provided in the following sections:

Storage system capacity metrics
Pool capacity metrics
Volume capacity metrics

Tip: IBM Spectrum Control displays capacity values in base 2 (GiB), while the XIV management GUI displays capacity values in base 10 (GB, TB). Even though different units of measurement are used, the storage values are equivalent.For more information about units of measurement, see Units of measurement for storage data.

Storage system capacity metrics

To detect capacity shortages and investigate space usage trends, you can add the following metrics to the capacity chart for storage systems:

Adjusted Used Capacity (%)

The amount of capacity that can be used without exceeding the capacity limit.

The formula for calculating Adjusted Used Capacity (%) is (Used Capacity in GiB/Capacity Limit in GiB )*100. For example, if the capacity is 100 GiB, the used capacity is 40 GiB, and the capacity limit is 80% or 80 GiB, then the value for Adjusted Used Capacity (%) is (40 GiB/80 GiB )* 100 or 50%. So, in this example, you can use 30% or 40 GiB of the usable capacity of the resource before you reach the capacity limit.

If the used capacity exceeds the capacity limit, the value for Adjusted Used Capacity (%) is over 100%.

To add the Adjusted Used Capacity (%) column, right-click any column heading on the Block Storage Systems page.

See these related values for more information Capacity Limit (%), and Capacity-to-Limit (GiB).

This metric is not available for all storage systems, such as Dell EMC VMAX.

Available Capacity (GiB)

(Previously known as Available Pool Space) The total amount of the space in the pools that is not used by the volumes in the pools. To calculate available capacity, the following formula is used:

(pool capacity - used capacity)

For XIV systems, pool capacity is the physical capacity of the pools and does not include the provisioned capacity of the pools.

Availability: All storage systems.

Available Volume Capacity (GiB)

(Previously known as Effective Unallocated Volume Space) The total amount of remaining space that can be used by the volumes in the pools. The following formula is used to calculate this value:

[Provisioned Capacity − Used Capacity]

The capacity that is used by thin-provisioned volumes is typically less than their provisioned capacity. Therefore, the available capacity represents the difference between the provisioned capacity and the used capacity for all the volumes in the pools. For Hitachi VSP non-thin provisioned pool capacity, the available capacity is always zero.

Availability: All storage systems.

Capacity (GiB): (Previously known as Pool Capacity) The total amount of storage space in the pools. For XIV systems and IBM Storage Accelerate, capacity represents the physical ("hard") capacity of the pool, not the provisioned ("soft") capacity. Pools that are allocated from other pools are not included in the total pool space.; Availability: All storage systems.

Capacity Limit (%) and Capacity Limit (GiB)

The limit that was set on the capacity that is used by your storage systems. For example, the policy of your company is to keep 20% of the usable capacity of your storage systems in reserve. So, you log into the GUI as Administrator and set the capacity limit to 80%.

Tip Click the illustration above to find out how to set capacity limits.

The GiB value for the capacity limit for the storage system is calculated when you set the value for the Capacity Limit (%).

To add the Capacity Limit (%) and the Capacity Limit (GiB) columns, right-click any column heading on the Block Storage Systems page.

See these related values for more information Adjusted Used Capacity (%) and Capacity-to-Limit (GiB).

This metric is not available for all storage systems, such as Dell EMC VMAX.

Capacity-to-Limit (GiB)

The amount of capacity that is available before the capacity limit is reached.

The formula for calculating Capacity-to-Limit (GiB) is (Capacity Limit in GiB - Used Capacity in GiB). For example, if the capacity limit is 80% or 80 GiB and the used capacity is 40 GiB, then the value for Capacity-to-Limit (GiB) is (80 GiB - 40 GiB or 80% - 50%) which is 30% or 40 GiB.

See these related values for more information Capacity Limit (%) and Adjusted Used Capacity (%).

This metric is not available for all storage systems, such as IBM FlashSystem A9000, IBM FlashSystem A9000R, and Dell EMC VMAX.

Compression Savings (%)

The estimated amount and percentage of capacity that is saved by using data compression, across all pools on the storage system. The percentage is calculated across all compressed volumes in the pools and does not include the capacity of non-compressed volumes.

For storage systems with drives that use inline data compression technology, the Compression Savings does not include the capacity savings that are achieved at the drive level.

The following formula is used to calculate the amount of storage space that is saved:

written capacity − compressed size

The following formula is used to calculate the percentage of capacity that is saved:

((written capacity − compressed size) ÷ written capacity) × 100

For example, the written capacity, which is the amount of data that is written to the volumes before compression, is 40 GiB. The compressed size, which reflects the size of compressed data that is written to disk, is just 10 GiB. Therefore, the compression savings percentage across all compressed volumes is 75%.

Availability: IBM FlashSystem A9000 and IBM FlashSystem A9000R, IBM Storage Accelerate, XIV storage systems with firmware version 11.6 or later, and resources that run IBM Storage Virtualize.

For IBM FlashSystem A9000 and IBM FlashSystem A9000R, all volumes in the pools are compressed.

Deduplication Savings (%)

The estimated amount and percentage of capacity that is saved by using data deduplication, across all data reduction pools on the storage system. The percentage is calculated across all deduplicated volumes in the pools and does not include the capacity of volumes that are not deduplicated.

The following formula is used to calculate the amount of storage space that is saved:

written capacity − deduplicated size

The following formula is used to calculate the percentage of capacity that is saved:

((written capacity − deduplicated size) ÷ written capacity) × 100

For example, the written capacity, which is the amount of data that is written to the volumes before deduplication, is 40 GiB. The deduplicated size, which reflects the size of deduplicated data that is written to disk, is just 10 GB. Therefore, data deduplication reduced the size of the data that is written by 75%.

This metric is available for IBM FlashSystem A9000, IBM FlashSystem A9000R, and resources that run IBM Storage Virtualize 8.1.3 or later.

Drive Compression Savings (%)

The amount and percentage of capacity that is saved with drives that use inline data compression technology. The percentage is calculated across all compressed drives in the pools.

The amount of storage space that is saved is the sum of drive compression savings.

The following formula is used to calculate the percentage of capacity that is saved:

((used written capacity − compressed size) ÷ used written capacity) × 100

Availability: Storage systems that contain IBM FlashCore Modules with hardware compression.

Mapped Capacity (GiB): (Previously known as Assigned Volume Space) The total volume space in the storage system that is mapped or assigned to host systems, including child pool capacity.; Availability: All storage systems.

Overprovisioned Capacity (GiB)

(Previously known as Unallocatable Volume Space) The capacity that cannot be used by volumes because the physical capacity of the pools cannot meet the demands for provisioned capacity. The following formula is used to calculate this value:

[Provisioned Capacity − Capacity]

Availability: All storage systems.

Shortfall (%)

The percentage of space that is over committed to the pools with thin-provisioned volumes. For example, you commit 100 GiB of space to a thin-provisioned volume in a pool with a capacity of 50 GiB. As the space is used by the thin-provisioned volume in increments of 10 GiB, the space available for allocation decreases and the shortfall in capacity becomes more acute.

To calculate the shortfall, the following formula is used:

[(overprovisioned capacity ÷ committed but available capacity) × 100]

A shortfall occurs when you commit more space to the volumes in the pools than is physically available to the pools. If the physical space available to the pools is less than the committed provisioned capacity, then the pools do not have enough space to fulfill the commitment to the provisioned capacity.

For example, the physical capacity of the pools is 70 GiB, but 150 GiB of provisioned capacity was committed to the thin-provisioned volumes. If the volumes are using 50 GiB, 100 GiB is committed to those volumes (150 GiB − 50 GiB) with only 20 GiB of available pool space (70 GiB − 50 GiB). Because only 20 GiB of the pool space is available, 80 GiB of the committed space cannot be allocated (100 GiB - 20 GiB). In this case, the percentage of committed space that is unavailable is 80% [(80 GiB ÷ 100 GiB × 100].

Availability: DS8000, FlashSystem storage systems, Dell EMC VMAX, VNX, and VNXe storage systems, Hitachi Virtual Storage Platform, SAN Volume Controller, Storwize family storage systems that are configured with block storage, XIV systems, and IBM Storage Accelerate storage systems.

Provisioned Capacity (%)

(Previously known as Virtual Allocation) The percentage of the physical capacity that is committed to the provisioned capacity of the volumes in the pools. If the value exceeds 100%, the physical capacity doesn't meet the demands for provisioned capacity.

To calculate provisioned capacity percentage, the following formula is used:

[(provisioned capacity ÷ pool capacity) × 100]

For example, if the provisioned capacity percentage is 200% for a storage pool with a physical capacity of 15 GiB, then the provisioned capacity that is committed to the volumes in the pools is 30 GiB. Twice as much space is committed to the pools than is physically available to the pools. If the provisioned capacity percentage is 100% and the physical capacity is 15 GiB, then the provisioned capacity that is committed to the pools is 15 GiB. The total physical capacity that is available to the pools is used by the volumes in the pools.

A provisioned capacity percentage that is higher than 100% is considered to be aggressive because insufficient physical capacity is available to the pools to satisfy the allocation of the committed space to the compressed and thin-provisioned volumes in the pools. In such cases, you can check the Shortfall (%) value to determine how critical the shortage of space is for the storage system pools.

Availability: All storage systems.

Provisioned Capacity (GiB): (Previously known as Total Volume Capacity)
The total amount of provisioned capacity of volumes within the pool. If the pool is a parent pool, it also includes the storage space that can be made available to the volumes in the child pools.; Availability: All storage systems.

Safeguarded Virtual Capacity (GiB): The percentage of the safeguarded virtual capacity of the volume that is physically allocated. The Safeguarded Virtual Capacity is collected during the daily probe for the volume level and can be viewed in at least the block storage system, volume, and pool panels. This field can be selected in the capacity charts.

Safeguarded Used Capacity (%)

The total amount of volume (virtual) capacity that is configured to store safeguarded backups for a safeguarded source. The Safeguarded Used Capacity is collected during the daily probe for the volume level and can be viewed in at least the block storage system, volume, and pool panels. This field can be selected in the capacity charts.

Safeguarded used capacity(%) = [Safeguarded Capacity (GiB)/Safeguarded Virtual Capacity (GiB)]*100

Safeguarded Capacity (GiB): The total amount of capacity that is used to store volume backups that are created by the Safeguarded Copy feature in DS8000.

Total Capacity Savings (%)

The estimated amount and percentage of capacity that is saved by using data deduplication, pool compression, thin provisioning, and drive compression, across all volumes in the pool.

The following formula is used to calculate the amount of storage space that is saved:

[Provisioned Capacity − Used Capacity]

The following formula is used to calculate the percentage of capacity that is saved:

((Provisioned Capacity − Used Capacity) ÷ Provisioned Capacity) × 100

This metric is available for IBM FlashSystem A9000 and IBM FlashSystem A9000R, IBM Storage Accelerate, XIV storage systems with firmware version 11.6 or later, and storage systems that run IBM Storage Virtualize.

Unmapped Capacity (GiB): (Previously known as Unassigned Volume Space) The total amount of space in the volumes that are not assigned to hosts.; Availability: All storage systems.

Used Capacity (%)

(Previously known as Physical Allocation)

The percentage of physical capacity in the pools that is used by the standard-provisioned volumes, the thin-provisioned volumes, and the volumes in child pools. Check the value for used capacity percentage to see:

Whether the physical capacity of the pools is fully allocated. That is, the value for used capacity is 100%.
Whether you have sufficient capacity to provision new volumes with storage
Whether you have sufficient capacity to allocate to the compressed and thin-provisioned volumes in the pools

Availability: All storage systems.

Used Capacity (GiB): (Previously known as Allocated Space) The amount of space that is used by the standard- and thin-provisioned volumes in the pools. If the pool is a parent pool, the amount of space that is used by the volumes in the child pools is also calculated.; The capacity that is used by for thin-provisioned volumes is less than their provisioned capacity, which is shown in the Provisioned Capacity (GiB) column. If a pool doesn't have thin-provisioned volumes, the value for used capacity is the same as the value for provisioned capacity.; Availability: All storage systems.

Pool capacity metrics

If sufficient data is collected, you can view charts that compare the capacity, used capacity, and available capacity of the pools in your data center.

In the Zero Capacity column on the Pools page, you can see the date, based on the storage usage trends for the pool, when the pool will run out of available capacity.

Zero Capacity: The capacity information that is collected over 180 days is analyzed to determine, based on historical storage consumption, when the pools will run out of capacity. The pools that have already run out of capacity are marked as depleted. For the other pools, a date is provided so that you know when the pools are projected to run out of capacity. If sufficient information isn't collected to analyze the storage usage of the pool, None is shown as the value for zero capacity. If a capacity limit is set for the pool, the date shown in the Zero Capacity column is the date when the available capacity based on the capacity limit will be depleted. For example, if the capacity limit for a 100 GiB pool is 80%, it is the date when the available capacity of the pool is less than 20 GiB. Depleted is shown in the column when the capacity limit is reached.

To detect capacity shortages and investigate trends in storage usage, you can add the following metrics to the capacity chart for pools:

Adjusted Used Capacity (%)

The amount of capacity that can be used without exceeding the capacity limit.

If the used capacity exceeds the capacity limit, the value for Adjusted Used Capacity (%) is over 100%.

To add the Adjusted Used Capacity (%) column, right-click any column heading on the Pools page.

See these related values for more information Capacity Limit (%) and Capacity-to-Limit (GiB).

Availability: This metric is not available for all storage systems, such as Dell EMC VMAX.

Available Capacity (GiB)

(Previously known as Available Pool Space) The amount of physical space that is available in the pool. If the pool is a parent pool, the amount of space that is used by the volumes in the child pools is also included.

Availability: All storage systems. For IBM FlashSystem A9000 and IBM FlashSystem A9000R, this value represents provisioned capacity rather than physical space.

Available Repository Capacity (GiB): The available, unallocated storage space in the repository for Track Space-Efficient (TSE) thin-provisioning.; Availability: DS8000 thin-provisioned pools.

Available Soft Capacity (GiB): The amount of virtual storage space that is available to allocate to volumes in a storage pool.; Availability: XIV systems, and IBM Storage Accelerate storage systems.

Available Volume Capacity (GiB)

(Previously known as Effective Unallocated Volume Space) The total amount of remaining capacity that can be used by the existing volumes in the pools. The following formula is used to calculate this value:

Provisioned Capacity − Used Capacity

The capacity that is used by thin-provisioned volumes is typically less than their provisioned capacity. Therefore, the available capacity represents the difference between the provisioned capacity and the used capacity for all the volumes in the pool. For Hitachi VSP non-thin provisioned pool capacity, the unused volume capacity is always zero.

Availability: All storage systems, except IBM FlashSystem A9000 and IBM FlashSystem A9000R.

Available Written Capacity (GiB): (Previously known as Effective Used Capacity) The amount of capacity that can be written to the pools before inline compression is applied. If the pools are not compressed, this value is the same as Available Capacity.
Important: Because data compression is very efficient, a pool can run out of Available Written Capacity while physical capacity is still available. To stay aware of your capacity needs, monitor this value and Available Capacity.

Capacity (GiB): The total amount of storage space in the pool. For XIV systems and IBM Storage Accelerate, capacity represents the physical or ("hard") capacity of the pool, not the provisioned ("soft") capacity.; Availability: All storage systems.

Capacity Limit (%) and Capacity Limit (GiB)

The limit that was set on the capacity that is used by your pools. For example, the policy of your company is to keep 20% of the usable capacity of your pools in reserve. So, you log into the GUI as Administrator and set the capacity limit of your pools to 80%.

Tip Click the illustration above to find out how to set capacity limits.

The GiB value for the capacity limit for the pool is calculated when you set the value for the Capacity Limit (%).

To add the Capacity Limit (%) and the Capacity Limit (GiB) columns, right-click any column heading on the Pools page.

See these related values for more information Adjusted Used Capacity (%) and Capacity-to-Limit (GiB).

Zero capacity: When you set the capacity limit for pools, the values shown for Zero Capacity are readjusted to take into account the capacity limit of the pool. The date will represent when the capacity limit of the pool is reached. If the pool has already reached the capacity limit, Depleted is shown. None is shown when a trend in storage consumption can't be detected because the pool's storage isn't being consumed or because not enough data was collected to predict storage consumption.

Availability: This metric is not available for all storage systems, such as Dell EMC VMAX.

Capacity-to-Limit (GiB)

The amount of capacity that is available before the capacity limit is reached.

See these related values for more information Capacity Limit (%) and Adjusted Used Capacity (%).

This metric is not available for all storage systems, such as IBM FlashSystem A9000, IBM FlashSystem A9000R, and Dell EMC VMAX.

Compression Savings (%)

The estimated amount and percentage of capacity that is saved by using data compression. The percentage is calculated across all compressed volumes in the pool and does not include the capacity of non-compressed volumes.

For storage systems with drives that use inline data compression technology, the Compression Savings does not include the capacity savings that are achieved at the drive level.

The following formula is used to calculate the amount of storage space that is saved:

written capacity − compressed size

The following formula is used to calculate the percentage of capacity that is saved:

((written capacity − compressed size) ÷ written capacity) × 100

Availability: IBM Storage Accelerate, XIV storage systems with firmware version 11.6 or later, and resources that run IBM Storage Virtualize.

Deduplication Savings (%)

The estimated amount and percentage of capacity that is saved by using data deduplication. The percentage is calculated across all deduplicated volumes in the pool and does not include the capacity of volumes that are not deduplicated.

The following formula is used to calculate the amount of storage space that is saved:

written capacity − deduplicated size

The following formula is used to calculate the percentage of capacity that is saved:

((written capacity − deduplicated size) ÷ written capacity) × 100

Availability: Storage systems that run IBM Storage Virtualize 8.1.3 or later.

Drive Compression Savings (%)

The amount and percentage of capacity that is saved with drives that use inline data compression technology. The percentage is calculated across all compressed drives in the pools.

The amount of storage space that is saved is the sum of drive compression savings.

The following formula is used to calculate the percentage of capacity that is saved:

((used written capacity − compressed size) ÷ used written capacity) × 100

Availability: Storage systems that contain IBM FlashCore Modules with hardware compression.

Enterprise HDD Available Capacity (GiB): The amount of storage space that is available on the Enterprise hard disk drives that can be used by Easy Tier for re-tiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Enterprise HDD Capacity (GiB): The total amount of storage space on the Enterprise hard disk drives that can be used by Easy Tier for re-tiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Mapped Capacity (GiB): (Previously known as Assigned Volume Space) The total amount of space in the volumes that is assigned to hosts. For Hitachi VSP non-thin provisioning pool space, this value is the sum of assigned regular host-accessible volumes. Volumes that are used for thin-provisioning (pool volumes) are not included.; Availability: All storage systems.

Nearline HDD Available Capacity (GiB): The amount of storage space that is available on the Nearline hard disk drives that can be used by Easy Tier for re-tiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Nearline HDD Capacity (GiB): The total amount of storage space on the Nearline hard disk drives that can be used by Easy Tier for re-tiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Overprovisioned Capacity (GiB)

(Previously known as Unallocatable Volume Space) The capacity that cannot be used by volumes because the physical capacity of the pool cannot meet the demands for provisioned capacity. The following formula is used to calculate this value:

[Provisioned Capacity − Capacity]

In thin-provisioned environments, it is possible to over commit (over provision) storage in a pool by creating volumes with more provisioned capacity than can be physically allocated in the pool. This value represents the amount of volume capacity that cannot be allocated based on the current capacity of the pool. For Hitachi VSP non-thin provisioned pool capacity, this value is always zero.

Availability: All storage systems, except IBM FlashSystem A9000, IBM FlashSystem A9000R, XIV, and IBM Storage Accelerate.

Provisioned Capacity (%)

(Previously known as Virtual Allocation) The percentage of the physical capacity that is committed to the provisioned capacity of the volumes in the pool. If the value exceeds 100%, the physical capacity doesn't meet the demands for provisioned capacity. The following formula is used to calculate this value:

[(Provisioned Capacity ÷ Capacity) × 100]

This value is available for all pools.

For Hitachi VSP non-thin provisioned pool space, the following formula is used to calculate this value:

[(Used Capacity ÷ Capacity) × 100]

Example: If the provisioned capacity percentage is 200% for a total storage pool size of 15 GiB, then the provisioned capacity that is committed to the volumes in the pool is 30 GiB. This configuration means that twice as much capacity is committed than is physically contained in the pool. If the provisioned capacity percentage is 100% for the same pool, then the provisioned capacity that is committed to the pool is 15 GiB. This configuration means that all the physical capacity of the pool is already used by volumes.

A provisioned capacity percentage that is higher than 100% is considered aggressive because insufficient physical capacity is available in the pool to satisfy the maximum allocation for all the thin-provisioned volumes in the pool. In such cases, you can use the value for Shortfall (%) to estimate how critical the shortage of capacity is for a pool.

You can hover the mouse pointer over the percentage bar to view values for the provisioned capacity and capacity.

Availability: All storage systems.

Provisioned Capacity (GiB): (Previously known as Total Volume Capacity) The total amount of storage capacity that can be made available to the standard- and thin-provisioned volumes in the pool. If the pool is a parent pool, it also includes the storage capacity that can be made available to the volumes in the child pools. For Hitachi VSP non-thin provisioned pool capacity, this value is the sum of the capacity of regular host-accessible volumes. Volumes that are used for thin-provisioning (pool volumes) are not included.; Availability: All storage systems.

Repository Capacity (GiB): The total storage capacity of the repository for Track Space-Efficient (TSE) thin-provisioning.; Availability: DS8000 thin-provisioned pools.

Reserved Volume Capacity: (Previously known as Unused Space) The amount of pool capacity that is reserved but has not been used yet to store data on the thin-provisioned volume.; Availability: Resources that run IBM Storage Virtualize.

Safeguarded Capacity (GiB): The total amount of capacity that is used to store volume backups that are created by the Safeguarded Copy feature in DS8000.

SCM Available Capacity (GiB): The available capacity on Storage Class Memory (SCM) drives in the pool. Easy Tier can use these drives to retier the volume extents in the pool.; Availability: IBM Storage Virtualize systems, such as IBM Storage FlashSystem 9100, IBM Storage FlashSystem 7200, and Storwize family storage systems that are configured with block storage.
SCM Capacity (GiB): The total capacity on Storage Class Memory (SCM) drives in the pool. Easy Tier can use these drives to retier the volume extents in the pool.; Availability: IBM Storage Virtualize systems, such as IBM Storage FlashSystem 9100, IBM Storage FlashSystem 7200, and Storwize family storage systems that are configured with block storage.

Shortfall (%)

The difference between the remaining unused volume capacity and the available capacity of the associated pool, expressed as a percentage of the remaining unused volume capacity. The shortfall represents the relative risk of running out of space for overallocated thin-provisioned volumes. If the pool has sufficient available capacity to satisfy the remaining unused volume capacity, no shortfall exists. As the remaining unused volume capacity grows, or as the available pool capacity decreases, the shortfall increases and the risk of running out of space becomes higher. If the available capacity of the pool is exhausted, the shortfall is 100% and any volumes that are not yet fully allocated have run out of space.

If the pool isn't thin-provisioned, the shortfall percentage equals zero. If shortfall percentage isn't calculated for the storage system, the field is left blank.

The following formula is used to calculate this value:

Overprovisioned Capacity ÷ Committed but Unused Capacity

You can use this percentage to determine when the amount of over-committed space in a pool is at a critically high level. Specifically, if the physical space in a pool is less than the committed provisioned capacity, then the pool does not have enough space to fulfill the commitment to provisioned capacity. This value represents the percentage of the committed provisioned capacity that is not available in a pool. As more space is used over time by volumes while the pool capacity remains the same, this percentage increases.

Example: The remaining physical capacity of a pool is 70 GiB, but 150 GiB of provisioned capacity was committed to thin-provisioned volumes. If the volumes are using 50 GiB, then 100 GiB is still committed to the volumes (150 GiB − 50 GiB) with a shortfall of 30 GiB (70 GiB remaining pool space − 100 GiB remaining commitment of volume space to the volumes).

Because the volumes are overcommitted by 30 GiB based on the available capacity in the pool, the shortfall is 30% when the following calculation is used:

[(100 GiB unused volume capacity − 70 GiB remaining pool capacity)
 ÷ 100 GiB unused volume capacity] × 100

Availability: DS8000, Hitachi Virtual Storage Platform, and storage systems that run IBM Storage Virtualize.

For IBM FlashSystem A9000 and IBM FlashSystem A9000R, this value is not available.

Soft Capacity (GiB): The amount of virtual storage space that is configured for the pool.; Availability: XIV systems and IBM Storage Accelerate storage systems.

Tier 0 Flash Available Capacity (GiB): The amount of storage space that is available on the Tier 0 flash solid-state drives that can be used by Easy Tier for retiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Tier 0 Flash Capacity (GiB): The total amount of storage space on the Tier 0 flash solid-state drives that can be used by Easy Tier for retiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Tier 1 Flash Available Capacity (GiB): The amount of storage space that is available on the Tier 1 flash, read-intensive solid-state drives that can be used by Easy Tier for retiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Tier 1 Flash Capacity (GiB): The total amount of storage space on the Tier 1 flash, read-intensive solid-state drives that can be used by Easy Tier for retiering the volume extents in the pool.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Tier 2 Flash Available Capacity (GiB): The available capacity on Tier 2 flash, high-capacity drives in the pool. Easy Tier can use these drives to retier the volume extents in the pool.; Availability: DS8000 storage systems.

Tier 2 Flash Capacity (GiB): The total capacity on Tier 2 flash, high-capacity drives in the pool. Easy Tier can use these drives to retier the volume extents in the pool.; Availability: DS8000 storage systems.

Total Capacity Savings (%)

The estimated amount and percentage of capacity that is saved by using data deduplication, pool compression, thin provisioning, and drive compression, across all volumes in the pool.

The following formula is used to calculate the amount of storage space that is saved:

Provisioned Capacity − Used Capacity

The following formula is used to calculate the percentage of capacity that is saved:

((Provisioned Capacity − Used Capacity) ÷ Provisioned Capacity) × 100

Availability: IBM FlashSystem A9000 and IBM FlashSystem A9000R, IBM Storage Accelerate, XIV storage systems with firmware version 11.6 or later, and resources that run IBM Storage Virtualize.

Unmapped Capacity (GiB): (Previously known as Unassigned Volume Space) The total amount of space in the volumes that are not assigned to hosts. For Hitachi VSP non-thin provisioning pool space, this value is the sum of unassigned regular host-accessible volumes. Volumes that are used for thin-provisioning (pool volumes) are not included.; Availability: All storage systems.

Used Capacity (%)

(Previously known as Physical Allocation)

The percentage of physical capacity that is used by the volumes in the pool, including the volumes in child pools. This value is always less than or equal to 100% because you cannot allocate more physical space than is available in a pool. Check the value for used capacity to see:

Whether the physical capacity of the pool is fully allocated. That is, the value for used capacity is 100%.
Whether you have sufficient capacity to provision new volumes with storage
Whether you have sufficient capacity to allocate to the compressed and thin-provisioned volumes in the pool

Availability: All storage systems, except IBM FlashSystem A9000 and IBM FlashSystem A9000R.

Used Capacity (GiB): (Previously known as Allocated Space) The amount of physical capacity that is used by the volumes in the pool. If the pool is a parent pool, the amount of space that is used by the volumes in the child pools is also included.; The capacity that is used by thin-provisioned volumes is less than their provisioned capacity, which is shown in the Provisioned Capacity column. If a pool does not contain thin-provisioned volumes, this value is the same as Provisioned Capacity .; Availability: All storage systems, except IBM FlashSystem A9000 and IBM FlashSystem A9000R.

Used Written Capacity (%): (Previously known as Effective Used Capacity) For devices with inline hardware compression, the effective used capacity percentage is the percentage of capacity that is provisioned to the standard-provisioned volumes and the thin-provisioned volumes, given the drive compression savings.
Used Written Capacity (GiB): (Previously known as Effective Used Capacity) The amount of capacity that is written to the volumes in a pool before inline disk compression is applied. If a pool is not compressed, this value is the same as Used Capacity.
Written Capacity Limit (GiB): (Previously known as Effective Capacity) The maximum of amount of capacity that can be written to a pool before inline-disk compression is applied. If a pool is not compressed, this value is the same as Capacity.

Volume capacity metrics

You use the capacity chart to detect capacity shortages for the following types of volumes:

Space-efficient volumes such as compressed volumes and thin-provisioned volumes
Standard-provisioned volumes that use Easy Tier® to re-tier volume extents

You can review the capacity usage by space-efficient volumes to detect capacity shortfalls. You can also review the capacity usage of volumes that use Easy Tier to distribute volume extents across Enterprise HDD, Nearline HDD, and SSD drives.

To detect capacity shortages and investigate capacity usage trends, you can add the following metrics to the chart for volumes:

Capacity (GiB): The capacity of the compressed or the thin-provisioned volume, which comprises the sum of the used and available capacity. For thin-provisioned volumes in XIV systems pools or IBM Storage Accelerate pools, capacity is the physical ("hard") capacity of the volume.; Availability: All storage systems.

Compression Savings (%)

The estimated amount and percentage of capacity that is saved by using data compression.

The following formula is used to calculate the amount of storage space that is saved:

written capacity − compressed size

The following formula is used to calculate the percentage of capacity that is saved:

((written capacity  − compressed size) ÷ written capacity) × 100

Availability: IBM FlashSystem A9000 and IBM FlashSystem A9000R, IBM Storage Accelerate, XIV storage systems with firmware version 11.6 or later, and resources that run IBM Storage Virtualize.

Exception: For compressed volumes that are also deduplicated, on storage systems that run IBM Storage Virtualize, this column is blank.

Enterprise HDD Capacity (GiB): The amount of volume capacity that Easy Tier has placed on Enterprise hard disk drives.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Nearline HDD Capacity (GiB): The amount of volume capacity that Easy Tier has placed on Nearline hard disk drives.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Safeguarded Capacity (GiB): The amount of capacity that is used to store volume backups that are created by the Safeguarded Copy feature in DS8000.

SCM Capacity (GiB): The amount of volume capacity that Easy Tier has placed on Storage Class Memory (SCM) drives.; Availability: IBM Storage Virtualize systems, such as IBM Storage FlashSystem 9100, IBM Storage FlashSystem 7200, and Storwize family storage systems that are configured with block storage.

Tier 0 Flash Capacity (GiB): The amount of volume capacity that Easy Tier has placed on Tier 0 flash drives.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Tier 1 Flash Capacity (GiB): The amount of volume capacity that Easy Tier has placed on Tier 1 flash, read-intensive drives.; Availability: DS8000 and storage systems that run IBM Storage Virtualize.

Tier 2 Flash Capacity (GiB): The amount of volume capacity that Easy Tier has placed on Tier 2 flash, high-capacity drives.; Availability: DS8000 storage systems.

Used Capacity (GiB): (Previously known as Allocated Space) The amount of space that is used by the compressed, thin-provisioned, or the Easy Tier volume. Typically, the space that is used by the compressed or thin-provisioned volume is less than the capacity of the volume. For Easy Tier volumes, used capacity is the capacity that is used by the volume's extents on the Enterprise HDD, Nearline HDD, or SSD drives.; Availability: All storage systems.

Written Capacity (GiB): (Previously known as Written Space) The amount of data that is written from the assigned hosts to the volume before compression or data deduplication are used to reduce the size of the data. For example, the written capacity for a volume is 40 GiB. After compression, the volume used space, which reflects the size of compressed data that is written to disk, is just 10 GiB.

Replication view

The following information show about the Replication Policy View:

ID: Indicates the name of the volume group.

Location 1 System: Indicates the location number 1 for the local system in the replication policy.

Topology: It represents organization of the systems and the type of replication performed between each location, that is, how the data is replicated between the locations.

Location 2 System: Indicates the location number 2 for the local system in the replication policy.

RPO Alert: Indicates the RPO alert threshold time (in seconds) for the replication policy.

Volume Groups: A volume group is a container for managing a set of related volumes as a single object. The volume group provides consistency across all volumes in the group. View the information that is shown about volumes in block storage systems.

Snapshot policy

The following information shown about the Snapshots: Snapshots:

State: The state of the fileset. Valid values are listed.

Safeguarded: The capacity that is consumed by all of the Safeguarded Copies for a source volume in IBM Storage Virtualize and DS8000. This value applies only to volumes that are the source in a Safeguarded Copy relationship.

Time Created: The time range is dynamically calculated based on the metrics created that are shown on the chart.

Expiring In: This status displays the number of days, hour, minutes left for the service to expire.

Limitations and known issues

Zero values are displayed for some metrics on storage systems that run IBM Storage Virtualize

Storage systems that run IBM Storage Virtualize with firmware 8.2 or earlier might show zero values for some capacity values. This issue occurs because the capacity values for these storage systems were changed to rely on physical capacity values.

The issue is resolved in newer versions of firmware, starting with the following versions:

8.1.3.6
8.2.1.4

For more information, see APAR HU01916: The GUI Dashboard and the CLI lssystem command report physical capacity incorrectly.