4

This question already has an answer here:

As I'm planning to buy an SSD and replace my old mechanical hard drive, I've heard rumors that having swap partition can decrease the life of SSD. So is this true? Or can I still have a swap partition on my SSD?

marked as duplicate by karel, Melebius, Eric Carvalho, pomsky, N0rbert Dec 13 '18 at 19:26

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • 1
    To some extent it was true when SSDs just came out. SSDs generally have lower lifetime ( in terms of writes to disk). So if your machine uses swap a lot - that is a lot of writes - that decreases SSD life expectancy. However, technology has become better over the years, so I'd suspect nowadays have just as good life expectancy as HDD in terms of writes. That's generally what the discussion comes down to - writes/reads to SSD and how agressively your machine uses swap. Of course, if you have good amount of RAM, small swap partition or swap file are good enough. – Sergiy Kolodyazhnyy Dec 13 '18 at 5:47
9

TL;DR: yes, it's OK to have swap on SSD, and swap partition is only one of many factors that may ( not necessarily will ) decrease SSD lifespan

Let's address the elephant in the room first: beginning with 18.04 release Ubuntu uses swap file instead of full partition ( see release notes ). So you won't have swap partition in the first place unless you yourself make one.

Now back to the topic. To some extent it was true that having swap partition may decrease SSD life when SSDs just came out. This has to do with the amount of writes that SSD can withstand and how aggressively your OS uses swap. To quote Wikipedia article on the topic:

If a particular block was programmed and erased repeatedly without writing to any other blocks, that block would wear out before all the other blocks — thereby prematurely ending the life of the SSD

So if your machine uses swap a lot - that is a lot of writes to that particular area of the drive - that decreases SSD life expectancy, even though other parts may be good. Note also that life of an SSD depends also on the particular technology used - cheaper drives use less reliable flash storage in general, and obviously more expensive - last longer with better flash storage. Other things affect SSD lifespan such as:

  • power outages and spikes
  • hibernation ( which saves a lot of RAM contents to disk )
  • temperature
  • if your SSD will be in datacenter environment, there's a potential that a lot of writes to log files can have an effect of lifespan, which I am guessing is why Debian suggests /var/log to be in persistent ramdisk.

ZDnet cites an article on the research performed by a professor at University of Toronto and Google, according to which one of the key conclusions is "SSD age, not usage, affects reliability." In other words, if this study is correct, even with high usage swap it's not going to drastically affect SSD reliability. Among other things, swap's primary purpose is to free up RAM so that more RAM is available to new processes. Well, with low swappiness setting and high RAM amounts nowadays, swap is used less and less, so it won't contribute as much to the lifetime of SSD.

It's also worth noting that swap partitions support TRIM according to answer on our fellow SO site Unix&Linux, which also plays a role in wear leveling - swap is not just wearing out SSD, but also has ability to engage SSD's built-in wear leveling mechanisms.

In conclusion, yes, it's OK to have swap partition and swap file, because:

  1. SSD life depends on multiple actors
  2. having swap or swap partition is still necessary to free up RAM memory that processes need
  3. with larger RAM sizes swap is used less and less nowadays, hence less worry about swap reads and writes contributing to wear

See also:

4

It's not rumor. Writing ANYTHING on SSD decreases the life of SSD.

But current life of SSD is reasonably long.

For example, the 256GB Toshiba nvme my own gaming laptop wears like 2.0x% a year, which means I can use it for 50 years before it wears out all NAND flash cycles. And I use hibernate a lot the first several months, which should impacts the life more than swap partition.

Also, my new WD Black 1TB nvme 3D TLC at work, with active android development(100GB repository after build-all), also wears less than 1%(I guess it's around 0.7%) after 3 months usage.

It totally depends how you use your drive.

The best way is that you just use swap partition normally, for several days or weeks, re-assess the wearing level using smart tools, and decide how you want to use it after.

  • 2
    “which means I can use it for 50 years” – are you sure this calculation makes sense? – leftaroundabout Dec 13 '18 at 8:51
  • I bought the laptop in 2017 oct, and in oct 2018 it has just passed 2%, so at wearing level's point of view, it could last 50 years. However we know in reality the hardware as a whole won't last that long. – Alvin Liang Dec 13 '18 at 8:54
  • 1
    What I mean is, a) is there any reason to assume that the “wear level” increases at a constant rate, and b) even counting out unrelated failure modes, would the drive still be practically usable at a wear level approaching 100%? – leftaroundabout Dec 13 '18 at 9:01
  • 1. From industrial experiences, if the task type and the percentage of space remains at same level, than the rate will be roughly the same. 2. wearing level is not optimistic estimation but strict lab verification. The quality of NAND will become unstable "after" wearing level is 100%. – Alvin Liang Dec 13 '18 at 9:19
  • I got a cheap old workstation with a 160GB SSD when my company threw it away. It was probably bought in 2009 or 2012 but when I checked the SSD I saw that it can be used for at least 10 years with the current data writing rate. Of course newer SSDs have much better wear-leveling algorithm as well as better write cycle, so it'll last a lot longer – phuclv Dec 13 '18 at 13:43

Not the answer you're looking for? Browse other questions tagged or ask your own question.