M4 Mac mini SSD (only 500 GB written) Available Spare dropped to 99%

FYI, I've rarely seen any Apple NVMe SSD to be at 100%. Most of them which I've checked are 99%.

Also, sometimes the manufacturer's don't always implement SMART reporting correctly. In fact, many times the manufacturer may implement these items backwards.

Usually any small changes should be ignored except for the values associated with "Media & Data Integrity Errors" which I find will usually show up where the user will actually encounter system related issues. These "Media & Data Integrity Errors" is the SMART attribute to be most concerned about. And possibly any "Error Information & Log Entries".

Like I said before, most SSDs will write PBs of data before wearing out so the "Available Spare" value should not really be much of a concern. I've rarely seen this value lower than 99% (unless the values were implemented in reverse of course where it would indicate "used" instead). Plus many of these NVMe SSDs (especially Apple's) don't show enough health information to really understand the true health of the SSD. Since you are paying close attention to this information, then just observe & learn how Apple's SSDs and the SMART information changes over time. This will tell you exactly how Apple has implemented these features.

Most SSDs will fail suddenly with absolutely no warning due to the SSD's controller failing. There is no health monitoring of the SSD's controller. Otherwise the "Media & Data Integrity Errors" and the "Error Information & Log Entries" are going to be the attributes of most concern for you at least from my own more limited observations of the Apple USB-C Macs' internal SSDs. You will drive yourself crazy otherwise. I've been using SMART to monitor HDs & SSDs for over 20 years to support my organization's computers (SSDs since around 2010/2012+).

Needless to say it was a bit alarming so I have done some research and it is quite common for Macs straight out of the box to report 99% Available Spare due to reporting glitches.

DriveDX states there is a known bug that causes this and it's quite common to pop back up to 100% later on.

It is a picture clipping from a recent EtreCheckPro report.

To be honest, I'm not concerned enough about the internal SSD life, to pay for DriveDX or use anything else.

If there are bugs or glitches in the test-ware you mentioned, then that would be on the developer to fix.

Yep, I have taken on board everything you have said in the past but as I said, seeing a virtually unused SSD apparently dropping 1% overnight was a bit of a shock, especially the Available Spare which should never be touched for years.

Ian R. Brown wrote:

If I had owned my M4 for 8 years I wouldn't be bothering either. 😉

The main point for sharing those stats, was that it has 19.26 TB written to it without any signs of degradation.

From what I have gathered is that the recent used is based on the estimated TBW lifetime time that a manufacturer has decided on. The TBW lifetime is based on manufacturer warranty more so than how long the drive will actually last.

Ian R. Brown wrote:

So you should be OK for another 400 years? (2% Used)

Give or take a few years.. All the more reason to just run from the Mac's internal SSD and use external SSD's for (Daily, Weekly, Monthly) CarbonCopyCloner clones that can used to rapidly move on to the next Mac.

Just a follow up to my original query.

Available Spare has jumped back up to 100% . . . in the 6 days since I first noticed it I have probably done a SMART test 4 or 5 times but it was stuck obstinately at 99% until just now.

Now that I have confirmed it was almost certainly a glitch I will not be doing frequent testing . . . just now and again.

Since first posting I have averaged under 10 GB of writes daily to my internal SSD (currently at 581 GB of writes since it was bought last year having been booting from an external).

So it should last me between 250 - 300 years.

Best wishes,

Nosferatu

I am still doing external booting off a 1TB OWC USB4 SSD which is nearly as fast as the internal. At the time, that SSD was less than Apple's 1TB SSD tax. However, these days, that same drive is more than the Apple 1TB upgrade price. This is pretty much true for the majority of reliable and fast 1TB SSDs not even considering TB5 solutions. So based on that, if I were to buy an M6 Mini today, I would just go for the 1TB internal and perhaps dual boot internal.

The SSD in our 2018 Mac mini has been on and in service 24-7 for 8 years.

What measuring app is that? It's not DriveDX or smartmontools.

Apparently the bug I mentioned only affects silicon Macs.

If I had owned my M4 for 8 years I wouldn't be bothering either. 😉

So you should be OK for another 400 years? (2% Used)

Which is what I am doing now that I have returned to the fold. Goodbye external boots.

👍