Power requirements
To assure predictable and reliable performance of the storage system in the data center, observe the appropriate power requirements.
Power cable usage guidelines
Hitachi storage systems are intended for rack installation and ship with power cords. Installation and service requirements may require additional cords and cables to be ordered. The type of power cable required by a given installation is determined primarily by the:
- Type of AC line feed provided by the facility.
- Type of AC source (wall outlet or modular and monitored PDU) to be used.
- Serviceability of components to be connected.
Storage systems require a country-specific power cable for direct connection to a facility AC feed.
Storage systems are designed to allow replacement of hot-pluggable components without removing the chassis from the rack. As a result, power cables can be short because cable movement is of minimal consideration.
Electrical requirements
The storage system requires two easily accessible power outlets near the rear of each controller. Each drive tray requires an additional power outlet.
The storage system controller and drive trays are equipped with two fully redundant wide-ranging power supplies that automatically accommodate voltages to the AC power source. The power supplies operate within the range of the storage system model:
- VSP F350 and 370 or G350 and G370: single phase 100-120 VAC or 200-240 VAC
- VSP F700 or F900 and G700 or G900: single phase 200-240 VAC
These requirements must be added to the power demands of any other electrical devices installed in the rack to arrive at a total power consumption figure. In addition, surge currents must be accommodated. Disk drives normally consume twice the amount of current at startup as they do during steady-state operation.
Power considerations
Hitachi storage systems have an input power rating of 125V–200V operation. The units come with a set of power cables.
A label near the power cord indicates the correct voltage, frequency, current draw, and power dissipation that should be used with the cable. Please be sure to use the appropriate power cable for your location. Also, check the power at your site to verify that you are receiving “clean” power (free of spikes and noise). Install a power conditioner if necessary.
Three-phase power considerations for racks
Increasing power requirements for racks are making the use of three-phase power at the rack level compelling.
- With single-phase power, at any given time the voltage across the hot and neutral conductors can be anywhere between its peak (maximum) and zero. Electrical conductors must be large to meet high amperage requirements.
- Three-phase power uses three cycles that are 120 degrees out of phase, which never allows the voltage to drop to zero. The more consistent voltage derived from the three hot conductors results in smoother current flow and allows small-gauge conductors to be used to distribute the same amount of AC power. As a result, the load balancing and increased power handling capabilities of three-phase distribution can result in more efficient and less costly installations that require fewer AC cables and PDUs.
Sources of electrical interference
Verify that the storage system is protected from sources of electrical interference.
The following table provides examples of electrical interference.
|
Potential source |
Description |
| Wall outlets | Power outlets for building maintenance and janitorial equipment, such as vacuum cleaners and floor buffers, must be wired from circuit breakers on a power panel separate from the computer system panel. The ground wires from these outlets must connect to the normal building distribution panel and not to the system ground. If a separate power source and separate ground are not provided, maintenance and janitorial equipment can induce electrical noise that can affect operation of the storage system. Your electrician can verify whether maintenance outlets are on separate panels. |
| Lightning | In geographical areas subject to lightning storms, you may want install lightning protection for your storage system. The principles of lightning protection and personnel safety are described in the National Fire Protection Association (NFPA) Handbook. |
| Electromagnetic interference | Electromagnetic interference can cause various problems. The storage system is designed to reduce its susceptibility to radiated and conducted interference. A Hitachi representative can advise you about common causes of electromagnetic interference. |
Branch circuits
Prepare your site to support the recommended power parameters of your storage system.
Plan to set up redundant power for each rack that contains a Hitachi VSP storage system. Supply the power with a minimum of two separate circuits on the building's electrical system. That way, if one circuit fails, the remaining circuit(s) should be able to handle the full power load of the rack. In addition, each Power Distribution Unit (PDU) within the rack should be powered by a separate power circuit.
Each circuit should be rated appropriately for the storage system model and input voltage. Refer to the storage system's electrical specifications for power requirements specific to each model.
Emergency power control
For safety purposes, consider installing emergency power-off controls for disconnecting the main power to the storage system.