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