Feeds

Drive suppliers hit capacity increase difficulties

PMR or HAMR for your platter?

Top three mobile application threats

Hard disk drive suppliers are looking to add platters to increase capacity because of the expensive and difficult transition to next-generation recording technology.

There are two candidates to replace the current Perpendicular Magnetic Recording (PMR) technology. The first is Heat-Assisted Magnetic Recording (HAMR) and the second Bit-Patterned Media. PMR becomes unstable once the magnetised areas become very small - they are subject to influence from neighbouring bits, among other interference. HAMR uses a media formulation in which heat is needed to write data, thus reducing such influence. BPM has a ring of insulating material around each bit to deal with the same problem.

Conversations with various industry-people, including Xyratex CEO Steve Barber, create a picture in which PMR has to be kept in use for four to five years because of the difficulty and expense of moving to either BPM or HAMR.

We have heard from Isilon and Buffalo spokespeople that hard disk drive (HDD) manufacturers have been talking about 4TB 3.5-inch drives arriving in the middle of 2011. We have also heard that there are 3TB evaluation drives out amongst OEMs.

Currently we have 2TB 3.5-inch SATA drives which have four double-sided platters inside them, with a read/write head per platter surface. Seagate has announced a 3TB FreeAGent GoFlex external drive but has not said what sort of disk drive is inside it. Our understanding is that it is a 5-platter 3.5-inch unit.

There are two ways to increase HDD capacity: increase the areal density per platter or increase the number of platters. We rule out increasing the size of the platters as that would increase the vibration at their edge and make the maintenance of the correct read/write head height more difficult. A platter size increase is also against the grain of HDD evolution and we are currently seeing a transition to 2.5-inch units. These employ a glass platter which is stiffer than the aluminium ones seen in 3.5-inch format drive.

Xyratex supplies drive array subsystems to IBM, Dell, EMC and NetApp. It buys an large number of disk drives and knows what is going on in the HDD industry. Barber says one HDD manufacturer is telling Xyratex that 3.5-inch drives are dead, with 2.5-inch the future, due to rebuild times: "2TB drive rebuild times are heading towards a week."

Technology transition costs

Barber says the fact the that HDD manufacturers are discussing 3TB drives with their customers indicates that they can't double densities as they have in the past. The costs and technical difficulties of a move to BPM or HAMR technology are huge: "The next-gen technologies work in the labs but are extraordinarily difficult to move into manufacturing. BPM manufacturing costs are off the scale; they'll need 12 to 14 per cent of [HDD manufacturer's] CAPEX [capital expenditure]." The current CAPEX percentage devoted to PMR manufacturing is rather less.

What will drive manufacturers do? End-users are growing data at a 50 per cent compound annual rate and the world needs disk drives to store it. "HDD suppliers will put more heads and platters into drives or ship more drives."

But datacentre floor space and power supplies are both limited. You can't simply double the number of storage arrays. The conclusion is that we're going to see more platters and heads inside disk drives. He thinks we could see three or four platters inside 2.5-inch drives, possibly even five. The laptop 2.5-inch drive bay slot needn't constrain enterprise arrays. We could see one, two or three platters with 3.5-inch drives.

That means that drive slots inside storage arrays will have to become larger. It's conceivable that you could add just one more platter and maybe shrink the overall height of the plaster stack to keep the drive enclosure depth unaltered, but add another two or three platters and a deeper clamshell case is needed. Increased platter-count drives will also draw more power.

High performance access to file storage

Next page: Shingle writing

More from The Register

next story
This time it's 'Personal': new Office 365 sub covers just two devices
Redmond also brings Office into Google's back yard
Kingston DataTraveler MicroDuo: Turn your phone into a 72GB beast
USB-usiness in the front, micro-USB party in the back
Dropbox defends fantastically badly timed Condoleezza Rice appointment
'Nothing is going to change with Dr. Rice's appointment,' file sharer promises
Inside the Hekaton: SQL Server 2014's database engine deconstructed
Nadella's database sqares the circle of cheap memory vs speed
BOFH: Oh DO tell us what you think. *CLICK*
$%%&amp Oh dear, we've been cut *CLICK* Well hello *CLICK* You're breaking up...
Just what could be inside Dropbox's new 'Home For Life'?
Biz apps, messaging, photos, email, more storage – sorry, did you think there would be cake?
IT bods: How long does it take YOU to train up on new tech?
I'll leave my arrays to do the hard work, if you don't mind
Amazon reveals its Google-killing 'R3' server instances
A mega-memory instance that never forgets
prev story

Whitepapers

Top three mobile application threats
Learn about three of the top mobile application security threats facing businesses today and recommendations on how to mitigate the risk.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.