HDDs Now Largely Beaten by SSDs in Term of Capacity

Now you can find 2.5-inch SSD at 8TB, for example in a recent drive launched by US company Foremay and that brings R/W speeds up to 500MB/s, and random R/W IO/s up to 100,000. During a recent investor webcast last week, Rob Crooke, SVP and GM of Intel non-volatile memory group, said coming 3D MLC NAND drives will allow for 10TB SSDs in two years and even suggest the arrival of  2mm thick mobile units at 1TB.
 
As of today, the highest 2.5-inch HDDs pack 2TB like the 6Gb SATA Seagate Spinpoint M9T at only 5,400rpm but with 9.5mm z-height, as the standard for 2.5-inch SSDs is 7mm. Maximum HDD capacity with 7mm is 1TB. There are also faster enterprise 2.5-inch hard disk drives with SAS interface at 2TB (Seagate Enterprise Capacity) rotating at 7,200rpm, but this time 15mm high, the same height being apply to Seagate Enterprise Perfomance 10K (1.8TB, 10,000rpm) and Enterprise Performance 15K (600GB, 15,000rpm).

For several years, HDD makers were proud to advance that their magnetic devices were leaders in term of capacity compared to SSDs. It’s not the case anymore. The records are now 6TB and 8TB, with 10TB coming next year form HGST with helium technology, but in 3.5-inch form factor. To reach this capacity in portable drives, the vendors will have to wait for new technology like HAMR at this time not available.

Several years ago, some SSD vendors designed 3.5-inch units, not anymore, everybody choosing now 7mm z-height to be easily integrated in notebooks and sub-notebooks.

More precisely the dimensions are 101x70x7mm or 49,490mm³ for the 7mm 2.5-inch form factor, and 147x102x26mm or 389,844mm³ or 7.9X more. This means that, theoretically, a 3.5-inch SSD could pack 62TB!

Now the last and only argument to opts for HDD rather than SSD is the price. 1TB rotating device at approximately $60 is approximately seven times more expansive than solid-state unit sold at around $420 for the same capacity. But this gap is regularly decreasing.

All the other characteristics are in favor of SSDs: much better access time, transfer rate and IO/s, and consuming less energy. The limited warranty is about the same number of years. With flash devices, the total terabytes written is limited but this spec is regularly improving.

The enhanced flash technology will also help USB keys with greater capacity, these ones consequently competing seriously with external HDDs.