View from the Labs
The mechanical hard disk may well be making its last hurrah in this Labs. James Morris reveals the factors behind its imminent departure
T hroughout this month’s Labs, we’ve focused primarily on the complete takeover by AMD processors. However, there was another visible trend: only three of this month’s systems contained conventional, mechanical hard disks.
For many years, the traditional configuration for workstations has been a smaller, fast SSD for the OS and applications with much larger, slower hard disks for general media storage. Only three systems this month deliver this configuration, though. At last, the benefits of SSDs over conventional hard disks are pulling ahead, with sizes growing and costs falling.
When SSDs first arrived, they were soon hitting the ceiling provided by the SATA 600 interface. While conventional hard drives were delivering 160 to 210MB/sec sustained throughput in our 2015 workstation Labs, SATA-connected SSDs were already achieving a 560MB/sec read rate. The differences in random access performance were even more pronounced. The NVMe interface had arrived, and SSDs using this PCI Express-based interconnect were breaching 1,000MB/sec – five times more than any hard disk at the time.
Fast forward to today and hard disks are closing in on 250MB/sec, so about 25% faster than they were six years ago. But now that SSDs have PCI Express 4 interfaces to call upon with the AMD platforms, drives are hitting over 6,700MB/sec – nearly 27 times the throughput of a conventional hard disk. The Armari Magnetar’s RAID0 array of two PCI Express 4 NVMe SSDs delivers a gobsmacking 13,000MB/sec – over 50 times faster.
Imagine you have a 4GB video file to work on. That will take 16 seconds to load from a conventional hard disk, and less than a second from a PCI Express 4 NVMe SSD. Of course, SSDs this fast still cost a considerable premium. But unless you’re working on video regularly, the 1TB and 2TB NVMe PCI Express 4 boot drives provided by most of the systems this month will be enough for everyday work.
More modest 2.5in SATA SSDs have also now come down in price sufficiently to make these viable to take the place of the large secondary hard disks of previous years. Two systems this month have opted for Samsung 870 QVO SSDs as secondary storage. The 4TB version of this drive will set you back around £280, twice the price of a 4TB business-class hard disk, but the SSD will deliver twice the sustained throughput and, most tellingly, a lot more than that with small file reading and writing in comparison due to much faster random access. SSDs consume far less power too: up to 3.2W when writing and a mere 35mW when idle, whereas the hard disk will be more like 7W when writing and 3.7W when idle.
We have QLC technology to thank for lower prices. This is where a single NAND flash memory cell has multiple layers so it can store four bits of data, compared to TLC’s three bits, MLC’s two bits, and SLC’s single bit. This has an implication for durability, but the 4TB Samsung 870 QVO, for example, is rated for 1,440TB written over three years. This is where business-class hard disks such as the WD Red Pro have an on-paper advantage: they’re rated for a typical one million hours, which equates to 114 years of continuous usage.
In reality, though, only a high usage data centre could have a problem with a 1,440TB writing limit. The SSD has had the performance crown over hard disks for years. With prices edging closer together, the writing is on the wall (or the flash memory cell) for the venerable Winchester drive format.
“At last, the benefits of SSDs over conventional hard disks are pulling ahead, with sizes growing and costs falling”