Saturday, July 08, 2023

Which Samsung SSDs for video?

This article will recommend which Samsung SSDs you should use for video recording... and which you should avoid. This article assumes that you wish to support high video resolutions and bitrates. For less stringent requirements you may get away with something else. But it makes the most sense to purchase accessories that support the most demanding mode of your camera, in case your requirements change in the future. 

Bottom line: The Samsung T7 Shield is recommended. Do not use the "plain" Samsung T7. The Samsung T5 is OK for lower rates. If you already have a Samsung T7 Touch, it will do as well. 

Test Results

This conclusion may confuse readers. After all, these drives all use a USB 3.1 Gen 2 interface. The T5 is an MSATA drive drive rated at 520 MB/s write speeds. Both the T7 and T7 Shield are NVME drives rated identically at 1000 MB/s write speeds. Samsung emphasises the robust build of the Shield but says nothing about the technical implementation. So what's the difference?

The problem is that the Samsung T7 has only a SLC (single level cell) cache. Once this is full, transfer rates drop. Samsung bases the advertised rate on how fast data is written to the cache, not how fast writes are made to the drive itself. We know this because Tom's Hardware has tested and compared the drives. The results are actually quite scandalous. 

The performance of the Samsung T5 500MB was tested 17 August 2017. Scroll down the article to the section "Full LBA Span Performance". You can see that the Samsung T5 (in both 500 MB and 1 TB capacities) out-performs the competition as it existed at that time, with a write speed of 365 MB/s. The fact that the curve is nice and constant is of primary importance when writing a video stream to disk. Any hiccups could mean dropped frames or even a corrupt file. 

Now view the second article, coincidentally published exactly three years later. Scroll down to the fourth chart, which has five pages. Check out image 2, which magnifies the x-axis from image 1. 

The sustained sequential write rate of the Samsung T7 (2 TB) starts at 867 MB/s but then drops to 337 MB/s as the cache saturates. This is much less than the advertised 1000 MB/s and even worse than the Samsung T5.

The Samsung T7 Touch (1 TB) is a smaller drive and so should have a smaller cache Sure enough, though it starts with a higher rate, this degrades sooner. But the drive nonetheless sustains 600 MB/s, more than the previous models. 

Now we move forward to 13 July 2022 and the test results for the T7 Shield. Scroll down again to the Sustained Sequential Write comparison and look at the second image. We see that the rate drops from the advertised 1000 MB/s after 22 seconds to about 900 MB/s. Still an excellent figure!

Here it's worth reminding the reader than SSD drives are consumer media. They are not designed for industrial video use. The fact they can be pressed into service for video gives us access to inexpensive media. But they are being manufactured as cheaply as possible, as a computer peripheral. If you want a professional solution, check out CFast media made by Angelbird and similar companies. These use multi-layer caches (MLC) to prevent write rate degradation. They cost significantly more. 

You get what you pay for. When using a Blackmagic camera, I stick with CFast media. 

Verified Media

Most manufacturers keep lists of verified media. The Blackmagic FAQ for their Pocket Cinema Camera 4K confusingly lists different products for different codecs and resolutions, but the Samsung T5 (1 TB or 2 TB) and Samsung T7 Shield (1 TB or 2 TB) are present throughout. Completely absent are the plain T7 and Touch T7 models.

The most demanding rate available in the BMPCC4K is when recording in BRAW 3:1, 4K resolution, 30 fps. This requires 405 MB/s. Technically, the T7 Touch does fit the bill. But Blackmagic have obviously made a decision to omit it based on other criteria. Perhaps the saturation of the cache and sudden drop in write rates produces other undesirable artefacts. 

Stepping up to the BMPCC6K, the most demanding recording is 6144 x 3456 in BRAW 3:1 at 50 fps. At this setting you get only 8 minutes of video on a 256 GB card, according to the camera manual. This is a bit rate of 535 MB/s. 

Checking the appropriate FAQ we find that this configuration is not even documented... which is odd. But for BRAW 5:1 compression we find the Samsung T7 Shield on the list... but none of their other models. This makes sense from the data we've surveyed.

The Panasonic verified media page recommends the Samsung T5 (500 GB, 1 TB, 2 TB) but the Samsung T7 Shield (1 TB, 2 TB) is still "Under Verification". At this point in this article, it's clear that the T7 Shield should perform admirably. 


Despite omissions and inconsistencies in vendor lists, the Samsung T7 Shield can be recommended for all recording formats of the BMPCC4K, BMPCC6K, and Panasonic Lumix S cameras. The 900 MB/s write rate is sufficient for even 6Kp50 BRAW footage. The Samsung T5 can be recommended for all 4K modes that require no more than 300 MB/s.

It's worth mentioning that there are plenty of drives from Angelbird, Delkin, Lacie, Wide, etc. that meet manufacturer specifications. But Samsung are the cheapest and most generally distributed brand, hence the present focus on their confusing line.


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