Home Forums Hardware Mac Desktops & Notebooks PCIe-based SSD

I'll soon be transitioning to a MacBookPro 15 (2017) with a PCIe-based SSD.

A significant use of my MBP17 is Home Sharing my iTunes Library (music & movies) with my TV4 over a home LAN. My MBP17's Energy Saver is set for Wake for Network Access. ...This has worked fairly well, although there have been instances (not many) I've had to bring MBP17 out of Sleep for the TV4 to access my iTunes Library.

Regarding the PCIe-based SSD, I am thinking about setting Energy Saver's Sys Pref for Computer Sleep to Never - for quick Home Share access. ....Recommend / Not Recommend?

[Display would be set for Sleep, after certain period.]

What issues long term (for the SSD), might result from setting the Sleep to Never?

None at all.

The SSD does wear out over time, but it's writing data to it, not leaving it powered up, that causes wear. Leaving the computer awake will not hurt the SSD in the slightest.

Am I correct in understanding that SSD, given it's solid state hardware, prefers a constant power-on condition, as opposed to Sleep & Awake from Sleep which electrically jolts the SSD more and thus, lessens longevity?

There is no evidence that a "jolt" from powering up an SSD has any effect one way or the other on longevity. There is all kinds of proof that an SSDs life span is reduced every time you write to it. Each data bit location on an SSD can only be written to a finite number of times. It can however be read virtually an infinite number of times. There is little evidence that limit will be reached before the system it is installed in will be replaced in normal use.

You might find this Wikipedia article helpful in explaining not only the operation of SSDs but the techniques used in their design and firmware to extend their useful lifespan.

Magnetic media also has limits on write operations, but those limits are much higher and seldom, if ever, reached before the drive fails mechanically or is replaced as part of a normal upgrade. Limited write life a real issue with the now infamous Zip drive that had a hard coded write lifespan that was easily reached in normal use.

I think power consumption of computers has become much less of an issue as of late. We're well into the territory where you have to consider accumulated wear from thermal-cycling of equipment due to frequent power-off and power-on. Hard drives spin down to save power, but in doing so they shorten their lifespan. Good for their EnergySaver ratings, good for your power bill, bad for your data, bad for your wallet. You have to pick your priorities.

Once you have an SSD in your computer and your display set to sleep after half an hour or so, you're probably at the ideal tradeoff. My laptop is my primary computer, and the only time it's not on is when it's in my bag because I'm going somewhere with it. (which actually doesn't happen too frequently) I probably have a 98% uptime on the average.

I also frequently remote into my laptop from work, and I also run a few other server-type machines at home that are on 24/7 as well. Uptimes of months are not uncommon. I do tend to reboot my laptop about every two weeks though because my frequent user activity on it will cause crud to gradually build up and start affecting performance.

The rub is think! Not to question your, or anyone else's, experience or authority but the issue of startup shock vs. system longevity has been around since at least the early 1970's to my personal knowledge. Knowledgeable users, technicians, and engineers have come down on both sides of this issue, and there have even been sporadic attempts at research, but as far as I know there has been no definitive study proving the case either way. But any such testing would be VERY expensive and given the rate of technological change the results would almost certainly be equivocal.

There are however two components in modern machines that have known finite limits.

• SSDs with a limited number of write cycles and
• Lithium ion batteries with a limited number of charge cycles

Those can be mitigated by technological "tricks" and in general they are high enough that the probability is the computer will be replaced long before either becomes a problem, but the battery will probably be the first to go.

FWIW the up time on all the computers around here are similar to yours and most accurately measured in weeks rather than hours. Part of that harks back to the 1970's argument about the shock factor when starting a rotating rust drive vs always spinning with no thought about power consumption. (Today I have over 700 square feet of solar panels on my roof -- so priorities do change. )

While it's true that the battery will likely be the first to go, there's a new "feature" in the new Macbook Pro that's very worrying to me:

In the new machines, the SSD is soldered to the motherboard.

The SSD has a finite life, and when it reaches the end of that life, you can't replace it. Every other computer made to date has a hard drive that can be replaced. In the new MBP, once you hit the wear limit on the SSD, you're done, that computer is junk, the end.

The battery can be replaced; the SSD can't. Soldering an expendable part to the main logic board seems...questionable to me.

Can you quantify an SSD's life in a meaningful statistic that will establish just how questionable it is? For instance, I'm quite certain that an SSD's life expectancy exceeds that of an AppleCare policy, but how does it compare to the life users expect from a computer (Edit: both considering and ignoring the fear factor), i.e. what percentage of users is really at risk?

(This fits neatly into my jaundiced theory of Apple's push to make their portables smaller being just a front for adding perhaps significant, perhaps even unnecessary cost to them under false pretenses.)

SSD life is measured in total writes, rather than in time, so it depends a lot on how much writing the user does.

I don't know what SSD is in the new MBP. The previous generation used Samsung EVO 830 chips. These chips offer pretty poor write endurance compared to other SSDs, and one particular sector can be written about 3,000 times before it fails. In practice, that amounts to about 78 TB written in a 128-GB drive. (By way of comparison, "pro" grade SSDs can be written more than 6,000 times before they fail, and the pro-grade chips are about on par with what Apple charges--a 2 TB Apple upgrade is $1,200.)

You can expect to have the drive last about 20 years if you write 10 GB a day. That's a lot for an average person who does little more than surfing the Web and writing emails and letters and so on. It's not a lot for me; I have, in the past week, averaged about 28GB a day as I've been working on the prepress for a graphic novel. A person doing video editing might write 40GB a day, which would eat the drive in 5 years.

20 years of endurance is certainly reasonable--few spinning-rust drives will last that long. 5 years is not.

There are things that people do that can cause massive writes in a short time. If you install a game like World of Warcraft on your computer, the act of installing it does about 18 GB of writes. If you install a game like Portal, you're looking at 11 GB of writes.

And because an SSD has to be rewritten an entire block at a time instead of one bit at a time, writing a large number of small files does "write amplification"--you may save 100 10KB files, but instead of writing 1,000 KB, you'll actually write 5,000 KB.

Thanks for the perspective.

Even considering your current work load do you really think you need to worry about reaching your SSD's write limit in 5 years (which just happens to be the Apple designated "useful" life of a Mac)?

It sounds like the only users who actually need to worry are the (I'll guess) veeery few who both write enormous amounts of data and can neither afford to upgrade their Macs as often as Apple thinks they should nor buy Mac Pros (which, I believe, have cost-mitigating user serviceable SSDs).

Even though their failure rate appears to be minuscule, I'm more inclined to worry about my SSD failing after my MBP's insurance has run out. (Conversely, though, SSDs tend to make extended AppleCare less important than it has been with HDDs.)

I just ran across OWC Makes MacBooks "Pro" Again with Game-Changing OWC DEC; it sounds like a viable solution to the problem if you've got a compatible Mac.

Edit: I just found OWC CEO Introduces the OWC DEC at the 2017 NAMM Show in which it's mentioned that the SSDs are user serviceable.

Wow, that looks like a slick piece of kit and no mistake.

Have you got any idea how it may interface with the motherboard?

IIRC from an earlier article in either MacRumors or 9to5 Mac, is physically attached by removing four screws that hold the bottom of the MBP case in place (the back is not removed) and replacing them with longer screws that pass through the OWC DEC and thereby hold both the original bottom and DEC in place. The electronic connection is through both of the USB C ports on one side of the MBP.

Thanks.

I just took another look, and it appears as though only one of the four USB C ports is involved. (I wonder if there'll be a similar solution for the 13" model with only two USB C ports?)

I understand that USB C is pretty versatile, but can all the functionality built into OWC's solution simultaneously pass through just one port?

And how might the SATA connection work, or will the extra drives be limited to functioning as externals?