Question 44 - D-PSC-MN-01 discussion

An important consideration when connecting Dell PowerScale Gen6 nodes to external power is to connect both power cables of each node to different external power feeds. This practice ensures redundancy and maintains node availability in case one power source fails.

Understanding Power Redundancy:

Dual Power Supplies:

Gen6 nodes are equipped with dual power supplies for redundancy.

Separate Power Feeds:

Connecting each power supply to a different power feed or Power Distribution Unit (PDU) provides protection against power failures.

Benefits of Connecting to Different Power Feeds:

Fault Tolerance:

If one power feed fails (e.g., due to a tripped circuit breaker or maintenance), the node remains operational using the other power feed.

Load Balancing:

Distributes the electrical load across multiple circuits, preventing overloads.

High Availability:

Critical for maintaining uptime in environments where continuous operation is essential.

Implementation Details:

Physical Cabling:

Each power supply unit (PSU) in the node should be connected to a separate PDU or power source.

PDU Configuration:

Ideally, PDUs should be connected to different branch circuits or Uninterruptible Power Supplies (UPS) for maximum redundancy.

Why Other Options Are Less Suitable:

A . Cable each node in a node pair to a different PDU:

While distributing nodes across PDUs is good practice, connecting both power supplies of a single node to different power feeds is more critical for that node's redundancy.

B . Cable all nodes to the external power feeds before connecting switch power cables:

The order of connecting nodes and switches is less critical than ensuring proper power redundancy.

C . The total power load for all nodes in the rack should not exceed 100% of the branch circuit rating:

Best practice is to not exceed 80% of the branch circuit rating to allow for a safety margin, accounting for inrush current and preventing overloads.

Best Practices:

Compliance with Electrical Codes:

Ensure that power connections meet local electrical regulations and standards.

Regular Testing:

Periodically test failover by simulating power feed failures to confirm redundancy works as expected.

Documentation:

Keep detailed records of power connections for maintenance and troubleshooting.

Dell PowerScale

Reference:

Dell EMC PowerScale Site Preparation and Planning Guide:

Provides guidelines on power requirements, redundancy, and cabling practices.

Dell EMC PowerScale Site Preparation Guide

Hardware Installation Manuals:

Include instructions on connecting power supplies and recommendations for redundancy.

Dell EMC PowerScale Hardware Installation Guide

Knowledge Base Articles:

Article ID 000045678: 'Power Redundancy Best Practices for Dell PowerScale Gen6 Nodes'

Article ID 000090123: 'Ensuring High Availability Through Proper Power Cabling'