Notes on tiering policy settings

  • If Auto is set as the execution mode, tier relocation is performed based on the monitoring cycle. Therefore, when the tiering policy setting is changed, tier relocation will automatically implement the tiering policy at the end of the current monitoring cycle. See Example 1 in Execution mode settings and tiering policy.
  • If Manual is set as the execution mode, you must manually perform monitoring, issue a monitor stop, and then start relocation (see Example 2, Case 1, in Execution mode settings and tiering policy). If you change the tiering policy settings while obtaining monitoring data, the monitoring data is used for the next tier relocation (see Example 2, Case 2, in Execution mode settings and tiering policy). Therefore, you do not need to perform new monitoring.
  • If a capacity shortage exists in the tier being set, a message may appear in the View Tier Property window that the page allocation cannot be completed according to the tiering policy specified for the V-VOL. Should that occur, the page allocation in the entire pool, including the tier that defines the tiering policy might not be optimized.
    NoteThe message that page allocation cannot be completed according to the tiering policy does not appear when these tiering policies are set:
    • All(0)
    • In a 2-tier configuration, Level2(2), Level3(3), or Level4(4) which is equivalent to All(0)

    When a capacity shortage exists in a tier, you can revise the setting of the tiering policy or the configuration of tiers. If the capacity of one tier is fully exhausted, the migrating pages are assigned to the next tier according to the tiering policy.

    • Level1(1): When tier 1 is full, the remaining pages are allocated to tier 2. If tier 2 is full, the remaining pages are allocated to tier 3.
    • Level3(3): When tier 2 is full, the remaining pages are allocated to tier 1. If tier 1 is full, the remaining pages are allocated to tier 3.
    • Level5(5): When tier 3 is full, the remaining pages are allocated to tier 2. If tier 2 is full, the remaining pages are allocated to tier 1.
    • Level2(2), Level4(4), and from Level6(6) to Level31(31): When the specified tier is full, the unallocated pages are kept in the prior tier or they are allocated to the tier that has free space. From Level 6 (6) to Level 31 (31), the names of tiering policies can be changed. If these names have changed, the new names appear.
  • If a performance shortage exists in the tier being set, pages may not be allocated in conformance to the tiering policy specified for the V-VOL. In that case, pages are allocated according to the performance ratio of each tier.

    As shown in the following table, allocation capacity considerations are based on the tiering policy.

    Tiering Policy

    Allocation capacity considerations

    All(0), Level2(2), or Level4(4)

    Tier range and I/O performance

    Level1(1), Level3(3), or Level5(5)

    Tier range

    From Level6(6) to Level31(31)

    First phase: Tier range.

    Allocation capacities in each tier.

    • Tier1: The setting value(%) in Tier1 Min.
    • Tier2: The value deducted Tier1 Max(%) and Tier3 Max(%) from 100(%).
    • Tier3: The setting value(%) in Tier3 Min.

    Second phase: Tier range and I/O performance.

    Capacities deducted from the mapped capacities of the first phase from the total used capacity, are mapped to each tier.

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