Backend Cable Connection

Reverse cabling can be used to connect enclosures in the ETERNUS DX.

For reverse cabling, the length of the provided cable between controller 1 (CM#1) and the last drive enclosure (connection destination) may not be enough. Longer cables may also be required according to the installation location of the enclosures in the same rack or the installation location of the enclosures in multiple racks.

The lengths of the backend cables should be taken into consideration when enclosure installation locations are being determined.

Two backend cables are provided as standard with each drive enclosure. For 2.5" NVMe type drive enclosures, 2.5" SAS type drive enclosures, and 3.5" SAS type drive enclosures, the length of the provided backend cable is 1.1m.

For extended connections, 3.5m, 6m, 15m, and 30m cables are available.

The type of backend cable differs depending on the cable length.

For connections between controller enclosures and 2.5" NVMe type drive enclosures, the cables with a length of 1.1m and 3.5m are Mini SAS HD copper cables, and the cables with a length of 6m, 15m and 30m are active optical cables. These cables are all used for NVMe drive enclosure connections.

For connections between controller enclosures and 2.5" SAS type/3.5" SAS type drive enclosures, the cables with a length of 1.1m, 3.5m, and 6m are Mini SAS HD copper cables, and the cables with a length of 15m and 30m are active optical cables. These cables are all used for SAS drive enclosure connections.

There are no operational issues even if different types of cables exist in the ETERNUS DX.

The following guideline shows how the backend cables should be used according to their cable length.

Table: Backend Cable Connection Usage
Cable length	Usage
1.1 m	Used when connecting drive enclosures in the same rack and the distance from the top board of the lower enclosure is 8U or less. Supplied with drive enclosures as standard.
3.5 m	Used when connecting controller enclosures with drive enclosures in the same rack, or when connecting drive enclosures in the same rack and the distance from the top board of the lower enclosure is 9U or more.
6m	Used when connecting to the enclosures in the adjacent rack.
15m	Used when connecting to the enclosures in racks that are not adjacent to each other.
30m	Used when connecting to the enclosures in racks that are far from each other.