## Understanding write-back and write-through modes on logical drives
(write-cache-mode option)

When using the write-cache-mode option, there are two available modes:

In write-back mode, the operating system sends data to the controller to write to a storage device. Subsequently, the controller sends a confirmation to the operating system before actually writing the data to the storage device. Doing so increases performance, but also contains an element of risk. For example, if there is a power failure, the data currently in the controller cache is lost. You can avoid this risk by installing a battery-backup cache device. This device preserves the data in the controller cache in the event of a power failure.

Attention:

1. It is possible to lose data if a power outage occurs while using the write-back mode without a battery-backup cache device.

2. If you do not have a battery-backup cache installed and enabled and you set this feature to the write-back mode, wait at least 10 seconds after your last operation before you turn off your system. Failure to follow this practice might result in lost data.

In write-through mode, the operating system sends data to the controller to write to a storage device. Subsequently, the controller writes the data to the storage device; then, sends a confirmation to the operating system. This mode can decrease performance, but contains no risk of losing data.