A storage administrator is tasked with creating a DR solution for block and file storage resources. The company has multiple regional and international sites containing a mix of Dell Unity XT and…

Question

Options

• ASynchronous remote replication should be restricted to within 161 km (100 mi) between sites to
• BSynchronous remote replication should be restricted to within 10o km (62 mi) between sites to
• CAsynchronous replication ensures zero data loss to the remote replica in disaster conditions.
• DAsynchronous replication over long-distance does not impact latency.

• A
  65% (24)
• B
  11% (4)
• C
  19% (7)
• D
  5% (2)

Explanation

Option A is correct because synchronous replication requires the source to wait for write acknowledgment from the remote site before completing the I/O operation. Beyond approximately 161 km (100 miles), round-trip latency becomes high enough to severely degrade primary storage performance, making synchronous replication impractical - Dell Unity documentation specifically cites this distance threshold.

Why the distractors are wrong:

• B uses the wrong distance (100 km / 62 miles). The actual Dell-documented limit is 161 km / 100 miles - a deliberate numerical trap.
• C is backwards: it's synchronous replication that guarantees zero data loss (RPO = 0). Asynchronous replication acknowledges writes at the source before they reach the destination, meaning a disaster can result in data loss equal to the replication lag.
• D is false: asynchronous replication over long distances absolutely affects the replication link - bandwidth consumption, replication lag, and queue buildup are all real concerns.

Memory tip: Use the phrase "Sync = Same moment, Short distance" - synchronous demands instant confirmation from both ends (hence the distance cap), while async is "send and move on," which trades latency safety for potential data loss (RPO > 0).

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