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SG0-001 · Question #309

You have an existing disk subsystem with 16 drives that provides volumes for six Windows hosts on 2Gb/s links. You decide to add another 16 drive tray to double the number of raw hard drives in order

The correct answer is B. The added server demand on the disk subsystem will saturate the ports.. Adding five new servers will likely saturate the disk subsystem's active port, as the increased demand approaches its maximum throughput capacity.

Storage Implementation

Question

You have an existing disk subsystem with 16 drives that provides volumes for six Windows hosts on 2Gb/s links. You decide to add another 16 drive tray to double the number of raw hard drives in order to support five (5) new UNIX servers. The average server throughput is 20 MB/s. The disk subsystem is dual ported and configured active-passive. What is likely to occur?

Options

  • AThe zone configuration on the fabric will control the traffic flow to the disk subsystem.
  • BThe added server demand on the disk subsystem will saturate the ports.
  • CThe disk subsystem will notice the extra servers and go active-active to support the load.
  • DThe Windows systems will receive precedence as they were registered first on the disk

How the community answered

(54 responses)
  • A
    13% (7)
  • B
    61% (33)
  • C
    6% (3)
  • D
    20% (11)

Why each option

Adding five new servers will likely saturate the disk subsystem's active port, as the increased demand approaches its maximum throughput capacity.

AThe zone configuration on the fabric will control the traffic flow to the disk subsystem.

Zoning controls access and visibility but does not directly control or prevent port saturation due to excessive I/O demand.

BThe added server demand on the disk subsystem will saturate the ports.Correct

The existing disk subsystem is active-passive with 2Gb/s links, meaning only one port provides an effective bandwidth of 250 MB/s. With 6 existing and 5 new servers, the total demand of 11 servers, each at 20 MB/s, totals 220 MB/s, which is close to the single active port's capacity, leading to saturation.

CThe disk subsystem will notice the extra servers and go active-active to support the load.

An active-passive disk subsystem will not automatically switch to active-active mode; this requires a different hardware configuration or manual intervention.

DThe Windows systems will receive precedence as they were registered first on the disk

Disk subsystems do not inherently prioritize I/O based on the order in which servers were first registered.

Concept tested: SAN performance calculation and port saturation

Topics

#performance prediction#disk subsystem#port saturation#capacity planning

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