Quick SAS Cabling Guide

Fault-tolerant Asymmetric Cabling Scheme

Although more complex to set up, the fault-tolerant asymmetric cabling scheme is the recommend way of connecting the expansion enclosures to the RAID array as it makes the enclosure loss protection possible.

Enclosure loss protection is an attribute of a disk group. Enclosure loss protection guarantees accessibility to the data on the virtual disks in a disk group if a total loss of communication occurs with a single expansion enclosure. An example of total loss of communication might be loss of power to the expansion enclosure or failure of both EMM modules. Naturally, the enclosure loss protection is not guaranteed if a physical disk has already failed in the disk group. In this situation, losing access to an expansion enclosure and consequently another physical disk in the disk group causes a double physical disk failure and loss of data.

Enclosure loss protection is achieved when you create a disk group where all of the physical disks that comprise the disk group are located in different expansion enclosures. This distinction depends on the RAID level.

For the diagram illustrating how to cable the specific configuration you have please see (hyperlink) Table 1

Note: An incorrect SAS cabling will be detected by the array system. The MD32xx/MD32xxi Storage Manager will warn you about the mis-wired enclosures by logging a major event in the event log. In addition, the Recovery Guru will point you to the mis-wire condition and provide you some guidance on correcting the problem. Please remember that a mis-wire condition will only be reported if incorrectly plugged SAS cables result in a non-working configuration. In theory, it is possible to attach the expansion enclosures in a technically correct manner, which will not be optimal but still be functional. The mis-wire events will not be logged for a configuration of this type.

Simple Cascade Cabling Scheme

The simple cascade cabling scheme could be used when the enclosure loss protection is not required. The advantage of using this scheme is the simplicity of the initial system set up.

For the diagram illustrating how to cable the specific configuration you have please see (hyperlink) Table 1

Diagrams

This section contains diagrams illustrating the MD32x/MD32xxi system configurations.

The last diagram (hyperlink) Figure 15 contained in this section is a special case: it contains picture of the labels which you can print, cut out and attach to the both ends of every SAS cable used in your configuration for an easy identification. If after initial wiring your array system has to be transported/moved then the labeled SAS cables will simplify the task of re-assembling the system.

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Dell MD3200i manual Fault-tolerant Asymmetric Cabling Scheme
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MD3200, MD3200i specifications

The Dell MD3220i and MD3200i are part of Dell's extensive line of modular storage solutions, designed to support organizations in optimizing their data management and scalability requirements. These models offer reliable performance and flexible features, making them suitable for various workloads including virtualization, cloud storage, and disaster recovery.

One of the standout features of the MD3220i and MD3200i is their support for iSCSI storage networking. By utilizing the Internet Small Computer Systems Interface (iSCSI) protocol, these systems provide organizations with a cost-effective way to connect their storage over existing network infrastructure, enabling efficient data transfers and management.

Both models are equipped with dual controllers that ensure high availability and failover capabilities, which are crucial for meeting uptime requirements in mission-critical environments. The dual controllers also facilitate load balancing and increase overall system performance, as they allow multiple paths to the storage, enhancing I/O performance.

Scalability is another key characteristic of the MD3220i and MD3200i. These storage arrays can be expanded to meet growing storage demands, supporting up to 240TB of raw capacity with up to 16 additional expansion enclosures. This flexibility allows organizations to start with a smaller configuration and grow their storage capabilities without a complete overhaul of the existing infrastructure.

The units also support multiple disk types, including traditional spinning disks, solid-state drives (SSDs), and a combination of both. This versatility enables users to tailor storage configurations to their specific performance and budgetary needs. Furthermore, the systems feature advanced data management technologies such as snapshots and remote replication, providing essential tools for data protection.

With their ease of management, the MD3220i and MD3200i are designed for straightforward configuration and operation. The intuitive management interfaces allow IT professionals to monitor performance, configure storage, and manage data effectively, ensuring businesses can maintain optimal system availability.

In summary, the Dell MD3220i and MD3200i are robust, scalable, and versatile storage solutions that cater to diverse organizational needs. Their integrated technologies, such as iSCSI support, dual controller architecture, and advanced data management features, make them an ideal choice for modern data centers looking to enhance storage capabilities while ensuring reliability and performance.
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