Serial ATA (SATA):
These are the basic hard drives in Dell PowerEdge servers. These have a few advantages over the older parallel ATA, including reduced cable size and cost, native hot-swapping, and faster, more efficient data transfer. SATAs are the cheapest drives, but their MTBF (mean time between failures) isn’t great. Most of the time SATAs fail on basic Dell server systems.
Near Line SAS:
These are enterprise SATA drives with an SAS interface, head, and media, and the rotational speed of traditional enterprise-class SATA drives with the fully capable SAS interface typical for classic SAS drives. Near Line SAS drives provide better performance and reliability than SATA drives. Basically, this drive is a hybrid between SATA drives and SAS drives.
Serial Attached SCSI (SAS):
SAS is a point- to-point serial communication protocol used in enterprise hard drives and tape drives, replacing the older parallel SCSI bus technology. SAS drives have higher RPM and are equipped with a bigger cache memory. These are the top-end in performance for electromechanical drives, but also much (much!) more expensive than SATA hard drives
Solid-State Drive (SSD):
An SSD is a data storage device that uses integrated circuit assemblies as memory to store data persistently. The development and increased use of SSDs has been driven a rapidly expanding need for higher I/O performance.
SSDs have much lower random access and read access latency than HDDs, making them ideal for both heavy read and random workloads. High-performance servers, lap- tops, and desktops, or any applications that need to deliver information in real-time, can benefit from SSD technology.
Non-Volatile Memory express (NVMe):
NVMe is a communication interface devel- oped specially for Solid State Drives (SSD). NVMe allows host hardware and software to get the most out of the parallelism made possible by modern SSDs. NVMe reduces I/O overhead and improves performance. NVMe is dramatically fast – the fastest drive that you can add to your server.