Upgrading or Replacing?

**Csargo** · 10-12-2018, 00:44

Originally Posted by Montmorency

Somewhat hijacking, but speaking of paging files: if a PC has an SSD primary and HDD secondary, is it (in)advisable to spread the paging file between both? I have 16GB of RAM otherwise.

For context, I found that I needed to have a large paging file (among other things) in order to play heavily-modded Skyrim a few years ago and I haven't changed the settings since. (I didn't keep the paging file entirely on the SSD in part because heavily-modded Skyrim takes up a huge amount of disk space.)

From what I've read the biggest problem with using an SSD for that purpose is it shortens the lifespan of the SSD, I'm not sure if that's correct and/or how significant the effects are to the SSD. I don't know if their would be a problem with spreading it across both, other than the I/O speed of an HDD is a decent bit slower than an SSD, but I don't think it would be inadvisable to do. I would just imagine that if it were spread across both you'd be at the mercy of HDD speed when trying to access that data.

**Husar** · 10-12-2018, 02:26

Well, yes, it's a bit weird/complicated.
A memory cell in an SSD deteriorates a little bit every time data is written into it. The deterioration is usually faster, the more data can be written into a cell. Some rather expensive SSDs used to have SLC (single level cell IIRC), which can take one Bit IIRC. MLC can take two and TLC can take three, possible that four bit cells are in development already. The manufacturing process in nanomaters can also affect the livespan, the smaller the cells are, the faster they should deteriorate. However, the controllers try to distribute write cycles and many SSDs come with extra spare cells that they can activate in case another cell deteriorates early and so on. So manufacturers have managed to keep the amount you can write before an SSD breaks pretty high using such techniques.

In earlier tests, many MLC SSDs could live for a long longer than the manufacturers guaranteed. I think they broke after a PetaByte was written to them or something like that. Usually the average write amount is given as 250TB TBW (Total Bytes Written) or thereabouts.
A page file can speed that up, but I think in many cases people will want to replace their SSDs with larger ones before they ever break due to write cycles, outside of heavy use scenarios.

Often scenarios are given, like you can write 50GB onto your SSD every day and it will still last you ten years. I don't think your average page file gets anywhere near that amount. At the very least since Windows 10, Windows is also aware of how to treat an SSD and will not defragment it in the background but use the TRIM command instead (some command to "clean up" an SSD without affecting the lifetime like defragmenting would).

All in all I wouldn't be too worried. Also consider that this means the larger the capacity of an SSD, the more you can write onto it before it breaks since every single cell in there gets written into less often if there are more cells to distribute the data to.

**Montmorency** · 10-12-2018, 03:18

Is there any way to monitor the state of the write life of the SSD?

**Husar** · 10-12-2018, 14:20

Originally Posted by Montmorency

Is there any way to monitor the state of the write life of the SSD?

Usually the manufacturers provide a tool for that. Might want to check their support website.

For me it's the Crucial Storage Executive, I'm not sure whether the tools work 100% with other manufacturer's drives.
This one provides data (SMART) on all my drives, but some functions, such as firmware updates, are only available for the Crucial SSD.
It gives the TBW for my SSD as ~12TB, I bought it around December 2015. For the HDDs, no TBW data is available though, don't know whether it would show that for the SSD of another manufacturer since I only have the one.

The SMART Data says Percentage Lifetime Used: 6% for the SSD, so I guess it can last a while longer. For the HDDs, that data point does not exist. Your best bet is to check with the manufacturer I guess.

Edit: Now that I checked the TBW, I realized I made a mistake last night. TBW meanst Total Bytes Written, not TeraBytes Written. I really should remember not to post in the night, or the morning, and perhaps not in between either.