Dell PERC (PowerEdge RAID Controller) and other controllers can support a variety of hard drive types. There are four main types used in Dell 9th generation servers and up. There are specific configuration limitations and the specifics should be checked for the type of controller used. In addition, the types cannot be mixed in the same RAID set. There is also transfer differences referred to as SATA 1, 2, or 3.
They may also be seen as 3Gb/s or 6Gb/s. In order to get the maximum speed the hard drive, backplane, cables, and controller all have to support the set rate. In most cases, the higher specification is backwards compatible to the lowest common speed.
Example - plugging a 6Gb/s hard drive into a 3Gb/s backplane will result in the speed being 3Gb/s.
Serial ATA (SATA):
SATA drives are base hard drives in Dell PowerEdge servers. Serial ATA was designed to replace the older parallel ATA (PATA) standard (often called by the old name IDE), offering several advantages over the older interface: reduced cable size and cost (7 conductors instead of 40), native hot swapping, faster data transfer through higher signaling rates, and more efficient transfer through a I/O queuing protocol.
On some systems without a controller, these can be cabled instead to the onboard SATA connections on the motherboard. On smaller servers with a controller, they can still be cabled because these systems will not have a backplane. Cabled hard drives are not hot swappable.