This section contains guidelines for properly placing and connecting the disk shelves.
For safety reasons, mount the heaviest equipment, typically disk shelves, at the bottom of the cabinet. Refer to the appropriate Oracle Safety and Compliance Guide for rack-mounting guidelines.
To best prepare for cabling controllers to disk shelves, now and in the future, mount controllers in the middle of the cabinet. This also allows for optimal air circulation, whether in a floor- or ceiling-cooled environment.
Do not remove cabinet panels to run cables between cabinets.
Balance the number of disk shelves across the disk chains in your system.
Balance the number of disk chains across the number of HBAs in your system. For example, attaching two chains to two separate HBAs will have better performance than attaching two chains to a single HBA.
Do not mix disks with different capacities or rotation speeds within a single disk shelf.
To maximize performance, use the maximum number of disk chains supported by the controller's SAS HBAs. For example, four SAS HBAs with eight chains and eight disk shelves will have better performance than two SAS HBAs with four chains and eight disk shelves.
To maximize performance, do not attach more than four DE2-24C, DE2-24P, or DE3-24C disk shelves to a single chain, and do not attach more than three DE3-24P disk shelves to a single chain. This only applies to systems that are performance critical. The maximum of six disk shelves per chain is available for cases where capacity is preferred over performance.
The maximum cable length between DE3-24 disk shelves is three meters.
The maximum cable length is six meters between DE3-24 disk shelves in a single chain that spans two adjacent cabinets.
The maximum cable length between DE2-24 disk shelves is three meters.
The maximum cable length between Sun Disk Shelves is three meters.
The maximum cable length between a controller and disk shelves is six meters.
Disk shelves are supported by specific HBAs in the controller, and can be combined in certain configurations within a system. Use the following table to determine the HBA type required by each disk shelf model.
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The following table describes which disk shelf models can be used together for which controller configurations, as of software release OS8.7.0. See Cabinet and Cabling Guidelines in Oracle ZFS Storage Appliance Cabling Guide for disk shelf intermixing guidelines and all-flash disk shelf usage. To understand which controllers support which HBA types, see Maximum Disk Shelves per Controller Configuration.
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