FATA and Midline drives are a tier below enterprise class 10K and 15K drives. Usually spinning at 7200 RPM, HP Midline / FATA disk drives use the same inexpensive and dense media found in workstation class SATA disk drives. On the EVA, HP has its OEM (Seagate) attach a Fibre Channel PCB (Printed Circuit Board) to a SATA HDA (head disc assembly), thus the acronym F-ATA. SAS MDL drives operate in the same fashion, only with a SAS PCB instead of FC. Other HP drives (such as those used in the MSA2000) use an interposer card to attach SATA drives to a dual port SAS controller. The benefit of these hybrid drives is dual-port (redundant) connectivity as well as SCSI error checking and correction which is greatly superior to the algorithms in the ATA standard.

Notice in Picture 1 how the HDA is identical between the FATA drive (left) and SATA drive (right.) Many lower-end HP MDL disks do not have an HP logo. The media is just as failure prone between both drives, BUT the SCSI (FC) error correction on the FATA drives makes data loss slightly less probable. The FATA drive also has two data channels on the SCA-40 Pin connector.

Notice in Picture 2 the INTERPOSER used to convert a single port (data channel) SATA disk to a dual port disk. This Interposer was used on HP P2000 / MSA2000 SANs. Even though it has a SCA-40 PIN connector, NO conversion to the FC Protocol is done. The Sierra-Logic chip is simply a multiplexer.

Picture 3 shows the native SCA-40 Pin FC connector on a FATA drive. SAS-NL drives will have a standard dual port SAS connector as well.

Picture 1: SATA vs. FATA Head Disc Assembly	Picture 2: HP SATA Interposer	Picture 3: FATA Connector

Midline and FATA disk drives use the same low-cost dense media found in desktop SATA drives. These drives are best suited for archival and non-random I/O. MDL drives have a short life span and tend to start growing defects after 2-3 years of use. As such, extra care should be avoided when buying any drives that are not FACTORY SEALED in HP boxes or refurbished by a qualified repair facility. Below are images from test software showing the true condition of a "new bulk" drive we have purchased: