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Fast Huge Storage Explained
Iain Anderson on Sat, June 14th 0 comments
As our applications and workflows demand more apps and more data, we find ourselves needing (craving?) larger capacity and faster storage. Iain Anderson explains the ins and outs in this article.

Introduction

While many people who deal with words or even still images don’t need to worry too much about storage, if you deal with video, suddenly it’s going to matter quite a lot. The internal drive won’t be big enough, and one external drive might not be fast enough. How can you get the fastest, largest storage possible?

Disks that spin and disks that don’t

The industry is currently transitioning from spinning platter hard drives, in which a head travels across several magnetic platters, to solid state hard drives, which has no moving parts and works much in the same way as a (very fast) thumb drive does. While spinning drives are currently much cheaper and larger, they’re nowhere near as fast—especially for tasks that involve reading and writing large numbers of small files. For this reason, a solid state drive (SSD) is an excellent idea for your Mac’s boot drive, and is either standard (Mac Pro, MacBook Pro, MacBook Air) or an option (iMac, Mac mini) across the range.

The top drive is very fast, but the lower drive holds four times as much.

The top drive is very fast, but the lower drive holds four times as much.

On the iMac and Mac mini, there’s also a hybrid option called Fusion Drive, where initial reads and writes take place on an SSD, but older files are moved to a larger spinning disk for the best of both worlds.

For the moment, though, larger storage is going to be on spinning disks. While 1 TB SSDs have recently become available, they’re still very expensive, so for anything other than the boot drive, look for something that spins, and just remember not to move it while it’s in use.  

Internal, external, what?

While the older Mac Pro allowed you to install several internal drives inside it, no current Mac allows this. There’s simply not space, and so you’ll need to look to an external solution. Most external cases power an internal SATA drive of some kind (spinning drives large or small, or a solid state drive) and provide one or more different interfaces for the connection. What to choose?

Ports fast and slow

Your Mac’s available ports will make a huge difference to the speed at which you can access data. Sometimes you can convert one port to another (though it’s not usually fast) and if you have an older Mac Pro, you may be able to add ports you’re missing. From slowest to fastest, then:

  • USB2 is the slowest standard, and a desktop-class USB2 drive might transfer just a litlte higher than 30 MB/s. Very slow, the lowest common denominator, avoid if possible.

Here’s about as good as USB2 gets.

Here’s about as good as USB2 gets.

  • FireWire 400, the older 6-pin version, can go a little faster at 35 MB/s or so. It uses less of your computer’s power while it does it, but it’s still slow by today’s standards, and not found on any current Mac. Avoid.
  • FireWire 800 can go about twice as fast as that, around 65 MB/s, but it’s neither fast, nor found on any current Mac. You can, however, purchase a Thunderbolt to FireWire adaptor, to make older drives work on newer Macs. If possible, avoid.

USB3 can go much faster again, matching the speed of any internal spinning mechanism, but falling short when faced with the fastest SSDs. Likely to top out at 300 MB/s with an SSD, but the fastest spinning disks today can only just hit 200 MB/s, and portable or older drives offer less than half that anyway. A future revision to USB3 promises to double this throughput, which will be a welcome update, but for now it’s the default, cheap industry option.

And here’s a Seagate Backup Plus 3TB drive through USB3.

And here’s a Seagate Backup Plus 3TB drive through USB3.

  • eSATA should match the speed of the internal SATA drive inside the mechanism, but this port has never been standard on any Mac. Thunderbolt-eSATA bridges are available, as are PCI cards for an older Mac Pro.
  • Thunderbolt is the best port yet available, and while it won’t be limited by the speed of the drive, it’s quite possibly overkill for a single spinning drive, because the bottleneck becomes the drive mechanism itself. It’s also expensive, often adding $200-300 to the cost of a drive. If you start combining multiple drives (called RAID) or looking at seriously fast SSDs, Thunderbolt is absolutely worth it—its real-world capacity is over 1000 MB/s. Thunderbolt 2, currently only in the new Mac Pro, promises to push this further, but Thunderbolt 1 is on all other current Macs.

Thunderbolt and USB ports on a MacBook Pro.

Thunderbolt and USB ports on a MacBook Pro.

Sizes large and small

The smallest SSDs might be just 64 GB, though they go up to 1 TB if you’ve got $700+ to spend. In the land of spinning disks, both smaller drives (bus-powered) and larger drives (requiring external power) are available, but portable drives are more expensive per GB and currently top out at 2 TB, while desktop-size drives are cheaper and go all the way to 4 TB. You might want a portable drive for field work, and larger drives for the office.

Here’s a portable Western Digital 1 TB and a desktop Seagate 3 TB.

Here’s a portable Western Digital 1 TB and a desktop Seagate 3 TB.

Normally, the sweet spot for price, performance and storage space lives a little below the bleeding edge, and at time of writing, the 3 TB desktop-size drives were a little faster than the 4 TB equivalents, while being cheaper on a $/GB scale.

All these technologies have their place, though. If you shoot on a Blackmagic Cinema Camera, you’ll need a fast SSD to shoot on, a spinning portable drive to copy it to in the field, and likely a big fat spinning desktop drive to store that footage long-term.

Faster and larger

The question presents itself: if SSDs are expensive and small, how do you store larger amounts of data for quick access? And how can you store truly monstrous amounts of data, like a 10 TB video project? And the answer is RAID.

Creating a RAID 1 array from two separate disks gives safety, but not space.

Creating a RAID 1 array from two separate disks gives safety, but not space.

RAID what?

Standing for Redundant Array of Inexpensive Disks, RAID is neither necessarily redundant nor inexpensive—though it can be both. You can buy an external enclosure which holds two, four, five or even more disks, then spreads your data across multiple disks for speed, security or both. Among the many options are:

  • RAID 0 (striped): data is split up written to multiple drives at once, for maximum speed, but if any drive in the RAID set fails, all data is lost. Provides the space of all drives combined.
  • RAID 1 (mirrored): the same data is written to two drives at once, for maximum security but with a slight speed loss compared to a single drive. Only half the total space of the drives is usable.
  • RAID 10 (collated): RAID 0 and 1 are combined to provide the speed of RAID 0 but with full redundancy. Requires four drives, but you only get the space of two.
  • RAID 5: data is written to multiple drives, but with clever redundancy to allow recovery should any one drive fail. You can use around 70% of the total space available, depending on how many drives are used.

Note: the data rates for RAID are often higher than most ports can provide. Even an external USB3 hardware RAID will often hit a real-world threshold of around 300 MB/s, far lower than a RAID 0 array might be expected to achieve. Thunderbolt RAIDs are usually much faster, but they’re expensive.

Hardware or software RAID?

Not all multiple-enclosure devices will actually provide RAID in hardware. Instead, they’ll rely on OS X’s built-in support to provide RAID 0, 1 or 10—but not RAID 5. If you want RAID 5, save your pennies and look to a new Thunderbolt 2 Promise RAID. If you just want fast RAID 0 (because you’re backing it up yourself) then perhaps a LaCie 5big will do. It’s still expensive, relies on software for RAID, but promises to be very fast as a RAID 0 box.

Still too pricey? Well, you can always just buy a couple of cheap USB3 drives and use Disk Utility to set them up as a RAID 0 set. You’ll get close to double the speed on reads and writes, and of course double the storage space with double the risk of failure. If you’re ready to back it regularly, this could be a very cheap, very capable solution.

With two desktop-size Seagate Backup Plus (~US$120 each) drives in RAID 0, the best speeds can be achieved by using two of the Mac’s USB3 ports, but you can still do a lot better than a single drive if you use just one port and a USB3 hub. If you keep the drives together, treat them well, and back them up very regularly, this is easily the cheapest way to get 6-8 TB of SSD-class speed.

Check this article to learn how you can create your own Frankenraid from spare USB3 drives you’ve got hanging around. With caution — enjoy!

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