Solid-state drives (SSDs) really are a marvel of modern engineering – their speed and robustness are slowly, but surely, being matched by price as key virtues. But SSDs are also slowly, but surely, killing themselves each time you write data to them, so it’s important to understand how they operate to maximise their working life and extend the time between replacements.
With that in mind, here are six essential tips to maximise your SSD’s lifespan, so you get the most value for your money.
TIP #1 – Don’t defrag. Ever
wdWe were always told ‘regularly defrag your hard drive to maintain faster access times’. On a mechanical drive, yes, that makes sense. But the thing that makes sense on a hard drive is the very thing that will send your SSD into an early grave. SSD seek times are so small that defragging is pointless anyway, even if it didn’t kill your SSD. So don’t do it. Ever. Or will come and take it off you!
TIP #2 – Get your TRIM on
Garbage Collection (GC) and TRIM are often confused – GC occurs in every SSD, but TRIM is the technique for minimising the amount data movement within the SSD, particularly when reclaiming abandoned blocks. Unlike a hard drive, you can’t simply write over the top of an SSD cell – it must be erased first, then the data written.
However, you also can’t erase individual cells – SSD cells are grouped together first as pages, then as blocks. You can write to a page, but can only erase a block. SSDs move data around to help facilitate creating erasable blocks – without TRIM, the SSD also moves abandoned pages unnecessarily, which adds to wear and tear. Read this primer from LSI Corporation for more.
While all new SSDs feature TRIM, you also need at least Windows 7, Mac OS X 10.7 (Lion) and Linux Kernel 2.6.33 to gain OS-side TRIM support. Linux distros don’t always enable TRIM (say, Ubuntu pre-14.04), so check before you dive in.
TIP #3 – Bulk up with a hard drive
Given SSDs are fast but expensive per gigabyte compared with hard drives, it makes sense to use an SSD as your system drive and grab a hard drive for secondary bulk storage of videos, images and other files where speed isn’t so much of an issue. With 1TB desktop drives selling for $65 or less, you may be able to get away with just a 120/128GB SSD for a system drive if you’re not into gaming. But as we’ll discuss shortly, there are good reasons for going to a larger 240/256GB drive if your budget allows.
TIP #4 – Don’t overload your SSD
capMore importantly, make sure you don’t fill your SSD to the brim. SSDs need some spare space for internal housekeeping as well as backup cells for those that die. That’s why I prefer 120 or 240GB SSDs as opposed to 128 or 256GB drives.
Internally, they’re the same capacity, respectively – the difference is the apparently smaller capacity drives hive off the extra space as ‘spare’, just like have a spare wheel in your car.
In general, it’s recommended you shouldn’t exceed 75 per cent of your SSD’s capacity in order to help to maintain performance levels – go beyond that and the drive performance dips.
TIP #5 – Go large on your SSD
ramThere are three main SSD cell types you can buy – single-level (SLC), multi-level (MLC) and triple-level (TLC) and they refer to the number of bits stored per cell. Bottom line, SLCs are good for up to one million program/erase cycles, MLCs up to 10,000 and TLC somewhere around the 1000 mark. Beyond those respective levels, the cells start to die off and forget/lose your data.
Naturally, SLC SSDs are more expensive than TLC types, but rather than fuss with cell type, the simple solution is to just buy a larger-capacity SSD.
How long does it take to kill an SSD? A bloody long time, as it turns out. Take Samsung’s 128GB-capacity ‘840’ SSD with its 1000-cycle rated TLC flash as an example and let’s say you write 10GB of data per day (the usual ‘average user’ figure). That 10GB doesn’t include other data the drive itself writes during normal functions such as garbage collection – the extra referred to as the ‘write amplification factor’ (WAF). Ideally, you’d like a WAF of 1x, meaning the data you save is the only data the SSD writes. If it’s 5x, the SSD writes 5MB for every 1MB of data you want stored (2-3x is considered ‘normal’).
Back to our 10GB per day, let’s say you have a 3x WAF, meaning the drive writes 30GB per day. With a 128GB capacity and 1000 write cycles, the formula is:
Lifespan (in days) = ( drive capacity in GB x write-erase cycles ) / ( data written per day in GB x WAF )
= (128 x 1000) / (10 x 3) = 4267 days or 11.7 years.
That’s a damn long time and I wouldn’t trust a hard drive to get near that. But it’s also an ‘average use’ lifespan, so you’ll have to adjust it for own usage patterns. To help, I’ve put this all into simple SSD Endurance Calculator.
TL;DR: the limit of SSD longevity is the number of storage cells multiplied by the number of program/erase cycles per cell.
In that context, having more cells (a larger-capacity SSD) has the same effect as having cells with more P/E cycles (MLC or SLC vs TLC). It’s thanks to a technique called ‘wear leveling’, which aims to ensure all cells get equal usage. So in theory at least, a 240GB SSD should automatically last twice as long as its 120GB counterpart and twice as long again as the 60GB version with exactly the same usage pattern.
TIP #6 – Crank up the RAM
But arguably the most important tip is there’s no point using an SSD to paper over cracks appearing elsewhere in your system – and primarily, we’re talking about insufficient system RAM. Windows’ pagefile system fires up and trashes the SSD every time you run out of RAM, so using an SSD when you have RAM issues is just plain dopey.
DDR3/4 RAM is down to $10-12 per gigabyte, so get your system complement up to 8GB at the very least before you start mucking around with an SSD (personally, I’d go 16GB but that’s just me). Even if you keep the same CPU, get the RAM and SSD setup right and you won’t recognise yourself!