A customer has concerns about high availability and single-point failure for their VSP environment and they are planning to implement a multi-pathing software. Which two Hitachi Dynamic Link Manager…

Question

Options

• AHDLM automatically redirects I/O operations to alternate paths if a failure occurs.
• BThe HDLM server monitors the client hosts' multi-pathing agents and redirects I/Os to an
• CHDLM collects path error information and preventively sets a path offline if the error threshold is
• DWhen a failed path becomes available, HDLM places the recovered path back online.

• A
  89% (24)
• B
  7% (2)
• C
  4% (1)

Explanation

Options A and D together describe HDLM's complete failover-and-recovery cycle: A covers automatic failover - when a path fails, HDLM immediately reroutes I/O to a healthy alternate path with no manual intervention - while D covers automatic failback - once a failed path recovers, HDLM restores it to service, keeping all available paths in rotation. This pair directly addresses both the high availability concern (no I/O interruption) and the single-point-of-failure concern (no one path is critical).

Why B is wrong: HDLM does not use a centralized server-to-client architecture; it is a host-resident agent that manages paths locally on each host independently - there is no "HDLM server" monitoring remote agents.

Why C is wrong: While HDLM does track path error statistics, proactively taking a degraded path offline reduces the available path count, which works against availability rather than directly supporting it - and the question asks specifically about features that assist HA and eliminate single points of failure.

Memory tip: Think of A and D as a complete loop - "down → detour → recover → return." A handles the detour when a path goes down; D handles the return when it comes back. If your answer doesn't include both halves of that cycle, it's incomplete.

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