## About Tray Numbering Conventions

Trays are numbered from the bottom to the top, starting with 1. The following illustration shows the tray numbers and where the controller trays are located in each possible array configuration.

Each array has a designated master controller tray and an alternate master controller tray. If the master controller tray fails, the alternate master assumes control of the array's operations. The master controller tray is the lowest controller tray in the pair until the first failover, as shown in the following table.

Tray | 2x2 | 2x4 | 2x6
--- | --- | --- | ---
Master | tray1 | tray 1 | tray1
Alternate master | tray2 | tray3 | tray4

For information on array host names and IP addresses, see About Conventions for Array Names and IP Addresses.

### Related Topics

- About Storage Trays
- About Arrays and Trays
- About Identifiers for Cabinets