Suppose I have a 512gb SSD on a Macbook Pro. I then want to temporarily (for a few days) store 300gb of content on that SSD. Then that 300gb will be deleted.

If done multiple times, would this process significantly affect the long-term performance or lifespan of the 512gb SSD? Something akin to fragmentation slow down? Basically, is it bad to fill up, then free up the space on my Macbook SSD?

For context, I am reformatting a backup drive, so I will store that 300gb on my Macbook for redundancy during the reformatting. But due to some problems copying, I have copied and deleted the data multiple times already.



There are two concerns here. Fragmentation and write tolerance. Here are some good articles on both:

Write Tolerance http://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead

While write tolerance on SSDs is a thing, several experiments like the one above have been performed showing they generally exceed manufacturer specifications on maximum writes, and while having a maximum write limit sounds like a scary thing, I would wager that an average HDD will likely fail before reaching those limits anyway (not because of the writes themselves but most hard drives probably don't see that much data over the course of several years). That being said it is still something to be aware of when selecting disk for a system that will have a high amount of writes, but for the case you describe I don't think it will take any more than a statistical 0 amount of life off your drive.

Fragmentation http://rtcmagazine.com/articles/view/101053 http://www.pcworld.com/article/2047513/fragging-wonderful-the-truth-about-defragging-your-ssd.html

Fragmentation can have a marginal affect on SSDs but again in your use case I don't foresee it being an issue.

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If you are simply deleting the file, you're probably fine; the blocks will simply be marked as free and used next time they're needed. If you're going to be DoD-wiping the blocks formerly contained by the data after they're no longer in use, that will strain the drive more.

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  • Thanks for reply. But does this mean that the process of 1) filling an SSD to capacity, then 2) freeing up its capacity again to a normal level (e.g. 50%) will not cause performance drop? Due to something similar to fragmenting for SSDs, or a limited write capacity? – newapartment Aug 11 '17 at 23:43
  • a dod wipe is essentially a three pass zero fill but generally they use a 7 pass. (Not recommended on an SSD, or at all unless you are a criminal) – jesse_b Aug 12 '17 at 0:00

Manufacturers provide along with their SSDs figures that can be used to estimate the lifespan of a particular SSD. One such spec is the terabytes written (TBW). This is simply an estimate of the total amount of data that can be written or re-written to an SSD before it becomes unreliable. This figure is accumulated over the SSD lifetime then expressed in terabytes.

For example, you may come across an SSD rated 220TBW. What this simply means is that 220 terabytes of data can be written and re-written to this drive with reliability guaranteed. In simpler terms, if your daily usage demands that you write 50GB of data to this drive, it will take about 12 years before the SSD is rendered unreliable. Many consumers just write a small fraction of 50GB to a drive on average. This implies that your drive can last much longer than the rated time.

Depending on how frequent you will be writing and rewriting the 300 GB of data, your drives lifespan will suffer. However, the performance will not be affected. Only the lifespan of an SSD is affected with the writing cycles. Find out more about SSD specifications here.

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