While super-fast flash storage has hogged the headlines, recent months have seen the available capacity of spinning disk HDDs increase to 6TB with the shipping since last September of HGST’s helium-filled SAS and SATA 3.5″ HelioSeal drives. This is a 50% increase on the previously available 4TB drives.
HGST has been able to do this because it has got a jump on its rivals by patenting a method of sealing helium into drives instead of air. Helium, famously, due to its ability to produce a funny voice when sucked from a party balloon, is about 1/7th the density of air.
This reduces friction against spinning components in the HDD, when they start up and as they run, and brings, says HGST – which thinks it has an 18 month/two year lead on the competition – a 36% decrease in power usage plus, crucially for capacity, the ability to run seven (thinner) platters in the drive rather than the usual five.
As if a 50% boost in capacity was not enough, we’re looking at the possibility of HDDs shipping with between 7TB and 10TB (with helium) by the end of this year and into 2015.
That’s down to the adoption of new ways of writing data to the surface of platters and consequent increases in areal density as the HDD makers move from the current standard of perpendicular magnetic recording (PMR) to the next generation shingled magnetic recording (SMR).
Then, two or three years down the road we’re looking at a tripling of current HDD capacities to around 12TB (with helium) with heat assisted magnetic recording (HAMR), which does what it says on the tin really, by heating up the surface of the drive and increasing the density of its storage capabilities.
It all sounds like great news until you think of the RAID rebuild times. These can currently stretch to days for 4TB drives that use the parity-based RAID levels (5 and 6) and will only get worse with capacities that double or triple that.
“It’s not good,” says HGST’s EMEA sales VP Nigel Edwards. “As capacities increase so will RAID rebuild times. It is an issue, but we are seeing huge demand and are being pushed for larger capacity drives.”
According to Edwards the future of such ultra-high capacity HDDs is in “cold storage“, ie archiving that sacrifices access times for ultra-low cost per TB. Here, if HDD makers can bring the cost per TB price of spinning disk down to that of tape, service providers will offer data archive services using vast amounts of disk drives that are spun up as customer access needs dictate.
It’s a plausible case. And it’ll be interesting to watch how it plays out. Because, as the HDD makers drive for ever-higher capacity disk the tape makers too – with a head start in terms of capacities/densities – are also looking at more archive-friendly technologies, such as LTFS and SpectraLogic’s Black Pearl implementation.
Oft-heard soundbite used to proclaim “tape’s is/isn’t dead”. Now it seems there’s a current of “disk isn’t dead” emerging and finding use cases to ensure its survival.