Nytro MegaRAID Overview : Nytro Controller Features and Benefits : Pinned Cache

Pinned Cache

Pinned cache is the process of the cached data getting destaged back into VD. This functionality can occur in three scenarios.

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Scenario 1: When some of the PDs in a source VD fail and the number of failures is more than the protection level, the VD is marked as Offline, and the associated cache data (if any) are pinned. If this case is handled and if the VD restored Online, the cached data are destaged into the VD.

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Scenario 2: When all of the PDs in a source VD are lost and if the VD gets deleted, the associated cached data with this VD are pinned. If this case is handled and if the VD is brought into the system as a Foreign Disk, during foreign import, the cached data are destaged into the corresponding VD.

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Scenario 3: When some of the Nytro Flash modules that are part of the cache pool are lost, the access policy of all of the associated source VDs that have cached data are blocked, and the cache data of the corresponding blocked source VDs are pinned. If the lost Nytro Flash module is restored Online, all of the blocked source VDs are unblocked, and all of the pinned windows are destaged.