A customer uses TrueCopy and ShadowImage with Hitachi AMS2000 modular arrays. They are interested in upgrading those systems to Hitachi Unified Storage (HUS). Which two benefits will the customer have

Question

Options

• ATrueCopy and ShadowImage will no longer require a DM-LU.
• BTrueCopy and ShadowImage will require less cache in the systems.
• CThe granularity of differential data being copied to the replication target has improved.
• DThe size of the DM-LU used for ShadowImage and TrueCopy will be reduced by about 50%.

Explanation

Correct answers: A and C

When upgrading from AMS2000 to HUS, Hitachi redesigned how differential data management works: HUS eliminated the requirement for dedicated Differential Management Logical Units (DM-LUs) entirely, so TrueCopy and ShadowImage no longer need them (A). Additionally, HUS improved the granularity of differential data tracking - meaning smaller, more precise blocks of changed data are identified and copied to the replication target, making replication more efficient (C).

Why B is wrong: Reduced cache consumption for TrueCopy/ShadowImage is not a documented architectural benefit of HUS over AMS2000 - cache usage is driven by workload patterns, not the DM-LU architecture change.

Why D is wrong: D contradicts A - if HUS eliminates the DM-LU requirement altogether, discussing a 50% size reduction is irrelevant; you can't reduce something that no longer exists.

Memory tip: Think "HUS = Zero DM-LU + Finer Granularity." The two upgrades go hand-in-hand - Hitachi internalized differential tracking (removing the DM-LU) and simultaneously made that tracking more precise (smaller granularity), both reducing overhead and improving replication efficiency.

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