The life expectancy of SSD in M1 MacBook
Introduction
There have been rumors about extensive writes operations to SSD on machines equipped with M1 chip [1]. As I was concerned about my M1 MacBook Air (16GB, 256GB SSD), I decided to actively monitor the use of SDD in my Mac.
I use my Mac for code development, machine learning, and data science for 5 days so my disk is rather used extensively.
In this article, I will show how much data is written to my SSD and if is there anything to be worried about (we will look at the Terabytes written or TBW). TLDR: There is nothing to be worried about! In my case, SSD will last from 5 to 50 years!
Endurance of the SSD
First, we have to take a look at how much TBW and SSD can take before they start to fail. It depends on the size of the SSD, used technology, and quality of chips used for SSD. How much the producers declare their SSD can withstand? As I have a 256 GB model I will use value for this model throughout the article. The larger the SSD the bigger TBW it can take.
Some popular SSD has been tested in the past [2–3]. We will focus here on the Samsung drives as Apple used their ships in MacBooks before [4]. The Samsung 840 Pro achieved over 600 TBW in the endurance test before it started to relocate sectors [2]. The Samsung 850 Pro achieved a whopping 9100 TBW before it started to relocate sectors [3]. Both tests are few years old but show that good quality SSD can withstand a lot of abuse. Below is a table showing how much TBW an SSD can take before it starts failing. All the data is expressed as TB [3].
+--------------+-------------+--------+-------------+-------------+
| Manufacturer | Model | SSD 1 | SSD 2 | NAND |
+--------------+-------------+--------+-------------+-------------+
| Crucial | BX200 | 187.8 | 283.1 | 16nm TLC |
| SanDisk | Ultra II | 690.9 | 749.3 | 15nm TLC |
| Toshiba OCZ | TR150 | 934.4 | 945.6 | 15nm TLC |
| Samsung | 750 Evo | 1203.6 | 1289.6 | 16nm TLC |
| SanDisk | Extreme Pro | 2836 | ? (>2330.7) | 19nm MLC |
| Samsung | 850 Pro | 9100 | ? (>2261) | 40nm 3D MLC |
+--------------+-------------+--------+-------------+-------------+The inspection of the M1 MacBook shows that Apple used a chip with the name SDRGJHI4 [5]. This means nothing but we can speculate that Apple probably used Western Digital chips [6]. As the disk is reported as an NVMe drive, we can pick some SSD drives from the Western Digital commercial OEM offer [7] that roughly matches the performance of SSD in MacBook.
The Western Digital PC SN530 NVMe SSD declares 200 TBW. The same value is declared for the SN720 drive. The Western Digital IX SN530 NVMe SSD declares 650 TBW. Very cheap WD Blue™ SN550 NVMe™ SSD can withstand 150 TBW. If Apple didn’t cheap out on SSD, in my opinion, it should withstand from 300–650 TBW for a 256GB drive. On the other hand, if we take a look at what people report we can see that probably Apple declares 1600 TBW for a 256GB drive. The users here [8] used 10% of the SSD lifespan and it is at 160 TBW which translates to 1600 TBW. Of course only if the smartctl tool is correct.
Here I assume that there are two scenarios. One that Apple used cheap but still good chips and the 256GB SSD has 300 TBW endurance, the other is that it has 1600 TBW endurance.
Method of monitoring
On my Synology NAS, I have an InfluxDB running inside a Docker container. With the use of a very simple python script, that I have written in less than 5 min which is running in the background I was able to read the value current of TBW and Units Written and send it to the database every minute and then plot it with Grafana.
Results
The results are shown below. Please note, that every value of the remaining days and years has to be multiplied by 2 for the plot where I show data for the last two days due to the way I calculate it in Grafana.
My Mac uses the RAM and SSD more often than in the case of normal usage because I use it to do some extensive calculations. But either way, my SSD will live from 8.8 to 9.2 years before it will reach 300 TBW with my use case. If the smartctl tool is correct about 1600 TBW endurance then it will live from 47–50 years. I have collected the data for around 6 days now and the report shows that I have a daily usage of around 100 GB written to disk on average.
Conclusions
Given that most of the time Apple uses high-end parts in their devices we can assume that Apple SSD has at least 300 TBW endurance. The worst-case scenario is that SSD has 150 TBW which will translate to about 4–5 years before my SSD will die. The realistic approach is that it has 300 TBW which gives me around 9 years of SSD lifetime. The most optimistic forecast is that it is capable of 1600 TBW, which will give me around 50 years before I will kill my SSD.
For now, I will assume that I have at least 9 years before SSD will show any signs of dying which is way more than I plan to have this laptop anyway.
Bibliography
- https://www.imore.com/m1-mac-users-report-alarming-hard-drive-health-readings
- https://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead/
- https://www.reddit.com/r/hardware/comments/6jk9j9/ssd_endurance_test_bx200_dead_after_187tb_850_pro/
- https://www.ifixit.com/Teardown/MacBook+Pro+15-Inch+Touch+Bar+Teardown/73395
- https://www.ifixit.com/News/46884/m1-macbook-teardowns-something-old-something-new
- https://www.reddit.com/r/hardware/comments/k010dg/is_onboard_ssd_in_m1_macbook_proair_or_mac_mini/gdgay53/?utm_source=reddit&utm_medium=web2x&context=3
- https://www.westerndigital.com/products/commercial-internal-drives?_ga=2.200323950.1311205439.1614194982-305229122.1613763066
- https://twitter.com/takkyun/status/1361768182625705986
