In today's fast-paced business world, keeping data safe and readily available is crucial. Smart Array controllers play a key role in this. They not only enhance the performance of storage systems but also help protect data. When data is moved to and from disk storage, it is temporarily held in a cache memory. This cache is part of the RAID array controller, which oversees the data transfer.

Letting the controller store (or 'cache') write data in its memory can speed up the writing process. However, this approach has a risk. It might lead the operating system to mistakenly think the data is already safely written to the disk. If a power failure occurs before the controller finishes writing the data, this could lead to data loss.

 

To prevent such data loss, RAID systems often include a battery backup. This backup keeps the data in the cache safe if the power goes out, until the system is turned on again. That's why it's essential to always have a functioning RAID battery. If the power supply unit (PSU) fails, or even if there's an uninterrupted power supply (UPS), the system could shut down. This might leave uncommitted data in your RAID cache at risk.

 

A working RAID battery ensures that this data is correctly written to the disk once power is restored. This is also true if there's a failure in the system board. Even if you need to replace the RAID controller, a working battery-backed cache can be transferred to a new card without losing any data.

 

However, the effectiveness of battery-backed caching depends on the battery's remaining life. To ensure reliability, it's advisable to replace the batteries every three years, unless other specific measures are in place.