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Iain Anderson on SSDs

Iain Anderson takes a look at the speed benefits and then the technical pitfalls of using a solid state drive for storing media - not all SSDs are made equal!

 

Solid State Drives are great, but they’re more complex than you may have thought. Importantly, while the very best SSDs perform very well indeed, many mid-range drives can fall short of their top advertised speeds. Let’s take a look at all the different variables at play to figure out what the best drive is for you and your budget.

old drivesAll those old spinning drives are for backups, I swear — I don’t have a problem

 

SSDs vs spinning disks

Today, you’d only really want to consider a spinning hard drive if you need a lot of storage on a single volume, either binding several disks together in a RAID setup, or as a large volume for backup or medium-term archiving.

I still use a pair of OWC Thunderbay units for office-based storage, and they’re great for storing many massive projects in the same place. Spinning disks have gotten huge lately, cruising past 10TB and 14TB to as much as 18TB in a single drive as of February 2021. But while all that space is certainly welcome — most SSDs top out at 2TB right now — a spinning disk is not as fast, portable or resilient as an SSD. 

OWC raid fcpYou still can’t beat a RAID for safe storage of massive amounts of data 

 

Moving parts make spinning disks easy to damage. I once saw a client knock over a spinning disk connected to his iMac; it died instantly, with hundreds of photos lost for good. Every time I see a portable spinning drive being moved while in use, I cringe a little — the risk is real. SSDs, by contrast, can be moved or even dropped while in use. Of course they’ll die eventually, as all drives do, but they’ll survive much more punishment, and some are even water resistant. They’re also smaller and lighter, ideal for mobile use, and one less thing to worry about on set.

Spinning drives have to spin up, so you’ll be waiting longer after plugging one in, and if you let them spin down (to lengthen their life) you’ll be waiting for that spin-up more often. And if you let a RAID array sleep while not in use, sometimes you’ll have to wait for all the drives to spin up again. Instant access is not the strength of a spinning disk, and the small pauses every time you try to find a file do add up. 

Once you’ve found a file you need to actually transfer the data, and spinning disks lose out here too. While an older spinning disk might top out at 150MB/s, even an older SATA-based SSD should come close to 500MB/s, a mid-range USB 3.2 Gen 2 drive should be around 1000MB/s, and an external NVMe-based Thunderbolt drive or the internal drive in a modern Mac should be somewhere around 2500-3000MB/s. Predictably, the best drives cost the most money, so it’s not feasible for everyone to spend top dollar on a high-end Thunderbolt SSD, or on a huge internal SSD in your Mac.

internal mac ssd sppedThe speedy internal drive on today’s Macs is a big part of why they feel so fast 

 

Can you use your internal SSD? 

It’s certainly possible to edit video from the internal SSD in your Mac, but most people prefer not to. It’s harder to transfer a job to another Mac should you need to, it’s easy to run out of space, and those internal drives are expensive. But for smaller jobs, and if you’ve got a solid plan for regularly archiving those jobs elsewhere — sure, go ahead. Here, I’ll assume you’re going to go external for most of your video storage needs.

What kind of SSD should you get?

There are plenty of external drives out there, and you can expect to pay more for higher speeds. The good news is that many of us don’t need to buy the most expensive drives, but even if you do, beware: you won’t always see the performance you may expect. The interface (some flavour of USB or Thunderbolt) is important, but there’s a surprising amount of variability in the SSD inside the enclosure too. All up, there are several reasons why you might not be able to push a drive to its maximum potential.

Let’s break them down, one at a time.

1. A copy moves at the speed of the slowest drive

First, and most obviously, you’ll only see top speeds if you’re transferring data from a drive that’s equally fast. The speed of a copying operation is limited by the slowest part in the chain, so even if you’re copying from an ultra-fast SD card (~300MB/s) or a fast SATA drive from to an external recorder (~500MB/s) you’ll never come close to maxing out the 1000-3000MB/s performance of a modern USB or Thunderbolt SSD. (For a large multicam shoot, using multiple card readers at once? That’s more possible.)

sd cards fcpNone of these SD cards are as fast as even a slow SSD

 

While it’s true that the internal SSD in most Macs is blindingly fast, most video editors are buying large SSDs to work on directly, not to copy data to and from the internal SSD. Unless you go for the largest and most expensive internal SSD, it won’t be big enough for most medium-sized video projects, and you therefore won’t be copying a lot of data back and forth to or from it. Short copies don’t take long, after all.

Therefore, even if you were to go for a high-end Thunderbolt SSD at 2500MB/s, you’d only see that speed if you buy two or more, and frequently copy between them. That’s potentially useful for quick turnaround work where you need near-instant transfers between Macs or for backups, but many backups can be made overnight, to larger spinning disks.

2. You can’t always write at full speed

Second, you’ll only see the top speeds of most SSDs for a short amount of time, but it’s not usually a problem with heat after use. It’s often because there’s a high-speed cache in most SSDs which data is written to first. When that cache fills up, write speeds slow down hugely — often to a slower speed than an older, cheaper SSD — until the cache recovers.

The very best SSDs can handle high speeds for a long time (or even indefinitely) but you’re certainly paying top dollar for those. You can’t simply trust quoted speeds because they might only be true for the first 30 seconds of operation. Just running Blackmagic Disk Speed test is not enough to really assess a drive and unfortunately that’s all that a lot of reviewers do.

Frustratingly, it can be quite difficult to find tests where truly large amounts of data are written — as is typical in a video workflow — but Tom’s Hardware and Anandtech do test this in their latest reviews. On Page 2 of a Tom’s Hardware SSD review, scroll down to their Sequential Steady State Write Workload graph and you’ll see the info video editors need.

toms hardware ssdIf you’re moving a lot of data, not all drives can maintain high speeds

 

There you can see that a Samsung T7 2TB can write at 867MB/s for just 100 seconds (84GB of data) before falling back to just 337MB/s — slower than an older, cheaper T5. Another example is the Crucial X8 where performance goes from 1050MB/s to 180MB/s after a few minutes of consistent writing. While that’s OK for many workflows (including video editing) the limitations can become obvious when you transfer a large amount of media in one hit.

So look out: on many low- and mid-range drives, the advertised high speeds can only be achieved for a short period of time. Smaller copies are very fast, but longer copies will slow down over time. Worse, the size of the high speed cache is usually a percentage of the total storage, so a 2TB drive will be able to manage a higher speed for longer than a 1TB drive, even if there’s plenty of space available on each.

3. Interfaces are a limiting factor

Thirdly, you might not be able to take advantage of the maximum speed that the drive interface offers. Thunderbolt (40Gbps) is still a better choice than USB (5-20Gbps), but it’s also still much more expensive, and potentially overkill if the SSD inside your enclosure doesn’t match up to Thunderbolt’s potential. If you need your drive to work on a PC as well as a Mac, remember that many PCs don’t have Thunderbolt, so the very fastest SSDs either won’t work at all, or might offer slower speeds over USB instead.

USB offers a whole extra level of confusion because of years of frustrating naming and renaming, but we can summarise. Most Macs support USB 3.2 Gen 1 at 5GBps (~500MBs speeds, older SSDs) and USB 3.2 Gen 2 at 10GBps (up to ~1000MB/s speeds) but be careful — not all ports on all Thunderbolt docks offer 10GBps speeds. This also isn’t a simple case of looking at the port, either: USB-A or USB-C might offer 5 or 10Gbps.

Today, almost no computers currently have USB 3.2 Gen 2x2 support (20GBps), so you probably won’t see those speeds (yet) if your drive (like the latest SanDisk Extreme Pro) supports that newest USB standard. If you’re chasing top speeds on a Mac, go for Thunderbolt at 40Gbps.

sandisk extremeA USB-C connection like this can offer a wide variety of speeds

 

There’s a further issue if you have a new (and otherwise excellent) M1 Mac, as there are issues with connecting many kinds of USB drives at their full speeds. It remains to be seen where the problems lie and if they can be fixed in software, but I currently see a ~20-30% speed hit when working with some common USB drives, including the T5 and a third-party enclosure. 

Unfortunately the M1’s USB ports connect some drives at 5Gbps instead of 10Gbps, and that can limit top speeds even with relatively slow SATA-based SSDs. In testing, my Samsung T5 1TB drive can write at 480MB/s when connected to a Thunderbolt dock connected to my M1 MacBook Air or direct to an Intel iMac, but at only 377MB/s when connected directly to an M1. Potentially worse at the high-end, OWC have identified an issue with write speeds on Thunderbolt drives, limiting the top speed to around 1000MB/s unless a Thunderbolt display is attached. 

This isn’t a big issue in the field if you’re copying from slower media than that, but it means that back in your office, you won’t see top speeds unless you use a Thunderbolt dock to sidestep the 5Gbps connection issue, and maybe even connect a Thunderbolt display to sidestep the second.

4. While editing, high speeds are often wasted

Fourthly, while copying files is a clear case where a pair of fast drives saves you time, that extra speed may not make any difference in terms of everyday editing. That’s because video data rates aren’t nearly as high as an SSD can offer, and there are other bottlenecks more likely to slow you down. ProRes in 1080p is under 20MB/s at normal frame rates, and you can comfortably play a few streams of that from a slow SSD without any problems. Multicam editing (and high speed skimming) is more likely to benefit from a faster drive, but regular editing with compressed media should be fine with most modern SSDs.

disk speed fcpEven 6 simultaneous streams of compressed 4K playing from a slow SATA SSD can’t trigger this warning

 

While the numbers in the BlackMagic Disk Speed Test might show a few crosses on some data rates, those red marks are all for uncompressed media — not something that most users ever encounter. If you want to online 8K ProRes multicams, you’ll want the very fastest, very largest drives you can find, but everyone else can relax.

Conclusion

This doesn’t mean you shouldn’t buy an SSD, just that there may be diminishing returns in chasing the very highest speeds. The advantages of any SSD in terms of latency, a big speed boost over traditional drives, smaller size and vastly increased robustness mean that they’re absolutely worth buying. But consider if your workflow can actually take advantage of the most expensive drives before spending a ton of cash on the very fastest Thunderbolt SSDs.

If a faster drive saves you just a few minutes of time every few days or even weeks, is it worth spending hundreds of dollars more? Conversely, could you get a larger, slower, but still fast-enough drive for the same amount of money as an ultra-fast one? Run the numbers against your actual workflow, and see what’s available to you.

envoy pro ex usbc frontandback v2If a higher-end option suits your workflow, check out OWC’s Envoy Pro drives 

 

OWC have some great options at the higher end and some good mid-range options too. For some time, the Samsung T5 has been widely recommended, but has now become much harder to find since the release of the newer, faster, and more expensive T7. Here in Australia, a 2TB T5 is AU$265 while a T7 is as least AU$440, and you’ll want to consider if the slowdown after 85GB of transfers makes the increased cost worthwhile. The newest version of the SanDisk Extreme (there are older, cheaper, slower versions too) seems like a decent mid-range drive without many compromises, though I haven’t tested it myself.

Another option: buy an internal SSD (SATA for cheap or NVMe for performance) and marry it up with a USB-C (cheap) or Thunderbolt (performance) enclosure to create your own personal solution — but it likely won’t be cheaper, nor as droppable, nor carry the same warranty.

If any drive manufacturers would like to send drives for review, I’m happy to throw a selection of heavy real-world tests at them (like copying 300GB of video files from the internal SSD) but until then, we’ll have to read between the lines. Look a little deeper than the Blackmagic Disk Speed test, and try to find tests which include real-world Mac-based Finder copies of over 150GB worth of files.

External storage for video editors is a special case. Your whole Mac benefits from the very quick speeds of a decent-sized internal SSD, but you’ll probably only really utilise the power of an external SSD when you copy a large amount of files to or from it. High end SSDs are great, but are they worth it to you? It’s your call, but either way — happy copying!

 

 


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Iain Anderson is a trainer and freelance editor based in Brisbane, Australia. Among other things, Iain is the author of Final Cut Pro Efficient Editing, an Apple Certified Trainer in Final Cut Pro, a lead trainer for macProVideo.com, a tutorial creator for coremelt.com, a videographer, an editor, an animator, a writer, a designer, and occasionally a coder of Apple Watch and iPad apps. In the past he’s created animations and live videos for Microsoft, virtual islands in Second Life for government, and screensavers for fun.

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peteramwiggins's Avatar
peteramwiggins replied the topic: #114654 25 May 2021 12:11
FWIW - As I tend to munch through Libraries, I set my cache to the desktop and then delete that when I've finished. No problems doing that so far and you get the full speed of the SSD.