Feeds

Buy Smarter: what you need to know about... HDDs

Bulk storage for your computer

  • alert
  • submit to reddit

Securing Web Applications Made Simple and Scalable

Drive Capacities

Disk capacity increases unabated, with 3.5in drives of over 2TB now readily available. As with memory cards, the best advice is to buy the highest capacity you can afford. It is always useful to have spare storage space in just about any device.

If you are buying for a desktop PC, though, it is worth considering buying two drives of half the total capacity you need, as it will provide much more versatile storage.

Distributing files between two drives gives added security in the event of disk failure, too. Even if you don't want the extra expense of a Raid 1 array, which gives you automatic backup by copy data to both drives, having files on two drives means you lose only half your data if a drive goes down.

Going for the two-drive approach does mean having two spare controllers on the motherboard of your PC, of course.

There's a price sweetspot for each type of hard drive, largely dependent on popularity. At the moment, it probably sits around the 1TB mark for 3.5in drives and 500GB for 2.5in.

This would be where you get the best deals in cost per gigabyte terms, with rates going up for noticeably higher or lower capacities.

Drive Speeds

Drive speed ratings depend on two main criteria: the spin speed of the disk platters and the amount of on-drive cache.

Typical speeds for 3.5in drives are 5,400rpm, 7,200rpm, 10,000rpm and, at a price, 15,000rpm. There are 2.5in drives available in the first three of these.

Average latency, the time taken for the drive heads to reach any point on the disk, varies from 5.5ms on a 5,400rpm drive down to 2ms on a 15,000 rpm one, so you do see a roughly linear increase in access speed with rotational speed of the disk.

The size of the memory cache fitted to a drive has less effect on its apparent speed, particularly when saving smaller files which fit completely inside the cache.

Typical cache sizes range between 8MB and 64MB, although there's little noticeable improvement in real-world terms with a cache much bigger than 8MB. Cache memory is cheap to fit so cache size tends to keep pace with increases in drive capacity.

Fitting a higher-speed hard drive will improve data-intensive applications but is not the first option in any PC upgrade. You will generally see a bigger performance improvement by adding more memory or fitting a faster processor.

And finally…

If you choose to fit an external drive with a USB 2.0 connection, bear in mind that the link will govern the speed of the drive.

A USB 2.0 port has a maximum theoretical bandwidth of 480Mbps, while a typical 7,200rpm hard drive can manage around 1Gbps.

Both give somewhat less than these rates in practice, but you can still see that you will get roughly half the speed out of a USB-connected drive compared with one linked directly to a drive controller.

USB 3.0 – aka SuperSpeed USB – Firewire or eSata, are better choices if you want to get the same speed from an external drive as you would from internal one. ®

Application security programs and practises

More from The Register

next story
iPad? More like iFAD: We reveal why Apple fell into IBM's arms
But never fear fanbois, you're still lapping up iPhones, Macs
For Lenovo US, 8-inch Windows tablets are DEAD – long live 8-inch Windows tablets
Reports it's killing off smaller slabs are greatly exaggerated
Microsoft unsheathes cheap Android-killer: Behold, the Lumia 530
Say it with us: I'm King of the Landfill-ill-ill-ill
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
Seventh-gen SPARC silicon will accelerate Oracle databases
Uncle Larry's mutually-optimised stack to become clearer in August
EU dons gloves, pokes Google's deals with Android mobe makers
El Reg cops a squint at investigatory letters
Apple orders huge MOUNTAIN of 80 MILLION 'Air' iPhone 6s
Bigger, harder trouser bulges foretold for fanbois
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.