German handlers deliver the first three hard disks with a capacity of 18 TByte. The WD Gold 18 TByte and Ultrastar DC HC550 18 TByte are sister models from Western Digital with SATA 6G ports. The manufacturer also offers the DC-HC550-HDD with SAS 12G as an alternative. All rely on Conventional Magnetic Recording (CMR), helium filling and a 512 MByte coarse DRAM cache.
Due to the same technology, the specifications are very similar: The WD Gold 18 TByte transfers up to 269 MByte of data. Both are rated for 550 TBytes of write volume per year with a five-year warranty. Western Digital estimates the Mean Time Between Failures (MTBF) to be 2.5 million hours. The Ultrastar model is marketed by the manufacturer for use in data centers, while WD Gold is aimed at end customers and smaller server operators.
ePMR increases capacity
Both hard disks use the Energy-enhanced Perpendicular Magnetic Recording (ePMR) technology as the first representative of the Energy-Assisted Magnetic Recording (EAMR) family, which Western Digital explains in a technical documentation: An electric current is conducted into the write head to generate an additional magnetic field and thus reduce the so-called jitter.
With reduced jitter, the platters can be written to more closely, which increases the data density – to 1022 gigabits per square inch in the case of the 18-TByte models. Additionally, tripartite write heads are used that can be fine-tuned, called Triple Stage Actuator (TSA) by Western Digital.
20 TBytes with SMR
Western Digital is currently shipping the 20TB Ultrastar DC HC650 to data center operators for qualification. Instead of Conventional Magnetic Recording (CMR), Shingled Magnetic Recording (SMR) with overlapping data tracks is used to increase the data density to 1160 Gbits.
The WD Gold 18 TByte is available from numerous dealers from a little over 590 euros. The sister model Ultrastar DC HC550 18 TByte costs at least 625 Euro – both with SATA 6G and SAS 12G.