10 questions to ask before expanding your storage
Buying a new SSD is fraught with danger, whether it’s choosing the incorrect interface, spending too much or choosing the wrong route. Here’s how to find the right drive
1 Am I looking for internal or external storage?
If you have the option of expanding your internal storage, that’s normally the neatest solution. It’s likely to give you the best performance too, as your new drive will be connected directly to the motherboard. Most desktop computers have space for you to install a second disk to work alongside your existing Windows drive. Alternatively, you might prefer to move your system wholesale onto a new, bigger drive: this keeps things simple, and if you pick a fast SSD then it can yield a noticeable performance boost. It’s not hard to “clone” your current system drive onto a new model ( see our feature on p38).
With many modern laptops and all-in-one systems, the main SSD is soldered in place, so your only expansion option is to attach external storage via USB. That’s not a problem – the latest USB 3 drives are fast and just as capacious as their internal counterparts. However, you can’t boot Windows or run applications off an external drive, so any performance boost will be quite limited.
2 Do I want an SSD or a mechanical drive?
In almost all cases we’d go for an SSD: they’re faster, lighter, smaller and more reliable than traditional mechanical disk technology. However, they’re also much more expensive on a per-gigabyte basis, so mechanical drives can still be a sensible choice if capacity is more important than performance – this month, we test two 4TB hard disks costing under £90, while an SSD of the same capacity will set you back at least £300.
“Most desktop computers have space for you to install a second hard disk to work alongside your existing Windows drive”
3 What’s the difference between SATA and M.2?
Drives manufactured to the 2.5in SATA standard use the same fittings and connectors as found in older laptops and compact PCs – so if you have a machine that’s trundling along with a small, slow hard disk, a SATA drive is an ideal drop-in replacement. You can also install a 2.5in SATA drive into a full-size desktop PC, although you may want to buy a bracket to fit it neatly into a 3.5in bay.
SATA drives aren’t the fastest option, however. They’re faster than a mechanical drive, but the SATA bus itself has a maximum speed of around 550MB/sec, well below what SSD chips are capable of.
That’s where the card-style M.2 design comes in. This newer standard fits directly into a slot on your motherboard and supports a technology called NVMe, which lets the SSD transfer data over a PCI Express x4 connection. Huge read and write rates of around 4GB/sec over PCI Express Gen3 thus become possible – rising to 8GB/sec if you have a recent PC that supports the latest Gen4 interface. While very few M.2 SSDs come close to those theoretical speeds, it’s enough headroom to allow even the cheapest model to outpace any SATA drive.
There’s just one gotcha to look out for: there are a handful of drives that use the M.2 format but connect over the SATA bus. Check that your chosen M.2 drive supports NVMe, or you’re likely to get far lower speeds than you’d hoped for.
4 So do I just need to buy a drive to match the connectors on my PC?
Not necessarily. If your de sktop PC lacks a spare M.2 slot, you can buy a cheap NVMe adapter card that plugs into a spare PCI Express slot. It’s not always possible to boot from a drive installed in this way, however – that’s down to your BIOS – and you will want to use an x4 slot (or higher) or you won’t get the drive’s full performance. You can also buy bare enclosures that connect a SATA or
M.2 drive to a USB port.
If performance is a priority for an external drive, check the connection details – the original USB 3 standard supports a maximum transfer speed of 600MB/ sec, but more recent revisions offer higher rates of 1.2GB/sec and 2.4GB/sec. Unhelpfully, these standards have had different names at different times, but right now the three variants are officially called USB 3.2
Gen 1, USB 3.2 Gen 2 and USB 3.2 Gen 2x2 respectively. You can plug any USB drive into any USB port, but to achieve top speeds the socket needs to match (or exceed) the standard used by the drive. If your desktop PC is stuck with an older standard, you can add Gen 2 or Gen 2x2 support via a PCI Express card.
5 Do I need to worry about SLC vs MLC?
In the early days of consumer SSDs there was much debate about the merits of SLC versus MLC. SLC (single-level cell) drives store a single bit of data in each physical memory location, while MLC (multi-level cell) drives store two or more. This makes MLC chips cheaper to manufacture than SLC, but it also makes them slower and reduces their lifespan.
Today, MLC technology has come on in leaps and bounds and most of the drives in this month’s Labs actually store three or four bits per cell. Does it matter? Not in isolation. The important things, as always, are price, performance and endurance. If those meet your requirements, there’s no need to worry about the underlying architecture.
6 How much space do I need?
There’s no single answer to that question. For most people, a terabyte of total storage will probably suffice for personal data, but if you like to play big games or edit collections of photos or videos, 2TB makes sense. If you choose a drive with plenty of headroom, you can also use the space for Windows’ File History feature, which lets you browse and recover old versions of files and folders.
When estimating your needs, err on the liberal side. Data has a habit of growing to fill the available space, and you won’t be happy if you end up having to upgrade again a year down the line. Invest in enough capacity to push that day off into the far future – that way, when the time finally comes, you can feel good about ab t moving up to a next-generation next-gene drive that’s bigger and faster fas than anything you could afford today.
“Manufacturers proudly advertise the estimated read and write speeds, but we recommend that you don’t blindly trust these”
7 What speed do I need?
Manufacturers proudly advertise the estimated read and write speeds of their drives, but we recommend that you don’t blindly trust these figures: as you’ll see from our graphs on p92, they don’t always square with what you’ll see in actual use.
We would also advise against rushing to buy the top-performing SSD in all circumstances. Yes, if you’re looking for a new system drive from which to run Windows and all your applications then you’ll want one that’s fast at both sequential and random access ( see “How we test” on p83). However, if you’re buying a secondary drive to house your collection of home videos and backed-up spreadsheets then sequential performance won’t make a huge difference to your experience, and randomaccess speeds are almost an irrelevance. It might be smarter to put the money towards a drive that’s slower but bigger.
8 Do I need encryption?
Several SSDs provide hardware encryption – in fact, you may already be using it without realising. That’s because all data is automatically, instantly encrypted at the point that it’s written to the drive and decrypted whenever it’s read back.
So what’s the point? The encryption key is typically stored in th the BIOS on your motherboard, and managed by the BitLocker function in Windows dows 10 Pro (or, for Windows dows 10 Home users, the “Device evice encryption” tool in n the Settings app). That means, if someone were to steal the drive and plug it into a different computer, the key would be missing, and they wouldn’t be able to read any of the data stored ored on it.
It’s easy to see why businesses nesses like this idea, but for individuals viduals it’s unlikely that someone’s going to try to steal your information. What’s more, using an encrypted drive can complicate things if you want to repair or upgrade your own PC. Still, there’s no harm in choosing a drive with hardware encryption – you don’t have to turn it on if you don’t want to.
9 What is write endurance?
The memory chips inside an SSD have a finite lifespan. Each time the controller electrically reprograms one of them, it becomes a tiny bit less reliable; eventually the drive will start to generate errors, or just die altogether.
Write endurance is a manufacturer’s estimate of how much data you can write to the drive before that becomes a realistic concern. It’s measured in terabytes written, or TBW: most 1TB SSDs promise an endurance figure of 600TBW, scaling up or down with capacity. Once you pass the TBW limit, your warranty expires (regardless of when you bought the drive) and all bets are off.
You can check how many gigabytes a drive has read and written using a free tool like CrystalDiskInfo, available from crystalmark.info. In practice, most consumer SSDs won’t ever reach their stated endurance – they’ll be replaced first with bigger, faster models.
Nevertheless, it’s worth taking reliability seriously: if a drive does fail – whether it’s in or out of warranty – it’s very hard to get your data back. TBW provides a relative indication of whether a particular drive is likely to stand up to heavy usage or whether it’s best reserved for a lightweight role – but you should keep backups in all cases.
10 Do I need extra software?
Some SSDs manufacturers provide software downloads for things such as monitoring your drive’s health or managing hardware encryption settings. With external drives, you might get a free backup utility. There’s nothing wrong with these tools, but don’t let them influence your buying choice: the same things can be achieved with free tools or features already built into Windows, and for the basic task of installing, formatting and using a new hard disk you don’t need any extra software at all.