To comply with the user requirements, the best options are to install the OS on a RAID 1 array, configure RAID 5 for the application data, and use SSD hard drives for the data application array. Here is why:
* RAID 1 is a mirroring technique that creates an exact copy of data on two disks. This provides redundancy and fault tolerance in case of hard drive failure. RAID 1 also improves read performance since either disk can be read at the same time. Therefore, installing the OS on a RAID 1 array meets the first requirement of separating the OS from the application data and protecting it from hard drive failure.
* RAID 5 is a striping technique with parity that distributes data and parity blocks across three or more disks. This provides improved performance and storage efficiency compared to RAID 1, as well as fault tolerance in case of a single disk failure. Therefore, configuring RAID 5 for the application data meets the second and third requirements of providing high IOPS performance and data availability.
* SSD hard drives are solid-state drives that use flash memory to store data. They have no moving parts and offer faster read and write speeds, lower latency, and lower power consumption than traditional HDDs. Therefore, using SSD hard drives for the data application array meets the second requirement of providing high IOPS performance.
References:
https://phoenixnap.com/kb/raid-levels-and-types
https://en.wikipedia.org/wiki/Standard_RAID_levels