Identifying shortfall before data is recalled from external storage

View the percentage of migrated data in external pools that does not fit into the available capacity on an IBM Storage Scale file system.

About this task

This percentage, called shortfall, represents the relative risk of not having enough internal file system space if you recall all data from the associated external pools. The higher the percentage, the higher the amount of migrated data that does not fit.

Procedure

To view the potential shortfall for a file system, complete the following steps:

  1. From the Resources menu, click File Storage Systems.
  2. Right-click a IBM Storage Scale storage system and click View Details.
  3. Under Internal Resources, click File Systems.
  4. Locate the file system that you want to check and view the value in the Shortfall column.

    To calculate shortfall, the following formula is used:

    [(External Pool Migrated Data − Available Capacity) ÷ External Pool Migrated Data] × 100

    For example, if the available capacity on a file system is 200 GiB, but the used capacity of migrated data on external pools is 500 GiB, the shortfall percentage is 60% (300 GiB). In this case, consider adding capacity to the file system before recalling data.

    [(500 − 200)÷ 500] × 100 = 60%

    If the file system has sufficient available capacity to contain all the migrated data in external pools, no shortfall exists. For example, if the available capacity on a file system is 500 GiB, and the used capacity in external pools is only 200 GiB, the shortfall is 0%.

    Tip: Only the space that is used by migrated data in external pools is included in the calculation for shortfall. Pre-migrated data is not included because it exists in both the internal and external pools.