Modern hard drives are designed to use the rotational energy in the spindle to quickly park the heads on a power failure. This is rougher than a graceful shutdown as you can typically hear the hard drive click relatively hard on a hard shutdown. As such, this process can cause accelerated wear, but should not be a cause for concern unless done very frequently. There is a SMART attribute for this, "Power-Off Retract Count", which is incremented when this happens, but it is not a pre-fail attribute.

However, recently written data may not have been committed to the platters proper. If writing is in progress, the hard drive will finish writing the current sector before retracting to the parking area so that sectors are never corrupted as a direct result of power failure. However, because data that has recently been sent to the drive may not have been committed to the platters (they are briefly held in the onboard cache for performance), that data may be lost on a power failure.

Modern hard drives are designed to use the rotational energy in the spindle to quickly park the heads on a power failure. This is rougher than a graceful shutdown as you can typically hear the hard drive click relatively hard on a hard shutdown. As such, this process can cause accelerated wear, but should not be a cause for concern unless done very frequently. There is a SMART attribute for this, "Power-Off Retract Count", which is incremented when this happens, but it is not a pre-fail attribute.

Although hardware damage should not occur, data loss is still possible. If writing is in progress, the hard drive will finish writing the current sector before retracting to the parking area so that sectors are never corrupted as a direct result of power failure. However, because data that has recently been sent to the drive may not have been committed to the platters (they are briefly held in the onboard cache for performance), that data may be lost on a power failure.