Cache size
The amount of cache memory provided in the controller.
Cache memory is used in RAID controllers (see "Type"). It serves to store the data that is most often used during the operation of the device: the cache provides high-speed access to this data, thus improving the overall performance of the controller. The larger the cache, the more data can be stored in it and the faster the device can work; on the other hand, large amounts of memory have a corresponding effect on the cost.
In the most advanced controllers, the cache may have special protection against data loss (see below for more details).
Cache protection
Function used in some advanced RAID controllers (see "Type") to protect against power failures.
Recall that when exchanging information through a RAID controller, this information is first written to the controller's cache, and then transferred "as intended". And since the cache uses volatile memory, when the power is turned off, all its contents disappear. This can lead to data corruption, sometimes quite significant.
Cache protection helps to avoid such troubles. It is usually implemented as follows: in addition to the actual cache, a non-volatile flash drive (NAND) is installed in the controller, as well as a supercapacitor that plays the role of a backup energy source. And if the main power fails, the information from the cache is rewritten to non-volatile memory (the energy of the supercapacitor is usually enough for such an operation with a margin) and is stored until the next power-on.
Thus, this feature in RAID arrays minimizes the possibility of data corruption due to power outages. The disadvantage of classic cache-protected controllers is their high cost.
Low profile
This feature means that the controller board has a small height; and the height in this case is how much the board protrudes above the "motherboard" in which it is installed.
Low-
profile components are mainly designed for use in compact form factors where there is no room for full-sized boards. However, nothing prevents installing such a board in a larger case.
