I bought an SSD and I am going to set up my desktop system with a completely fresh Linux installation.
SSDs are known to be fast, but they have a disadvantage: The number of writes (per block?) is limited.
So I am thinking about which data should be located at the SSD and which at the HDD drive. Generally I thought that data that changes frequently should be placed on the HDD and data that doesn't change frequently can be put on the SSD.
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Now I read this question, with a similar scenario. In the answers there is written: "SSD drives are ideally suited for swap space…"
Why are SSDs ideally suited for swap space? OK, I see high potential for raising the system's performance, but doesn't swap data change frequently and hence there would be many writes on the SSD resulting in a short SSD lifetime?
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And what about the /var directory? Doesn't its contents change frequently, too? Wouldn't it be a good idea to put it on the HDD?
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Is there any other data that should not be located on an SSD?
Best Answer
If you worry about write cycles, you won't get anywhere.
You will have data on your SSD that changes frequently; your home, your configs, your browser caches, maybe even databases (if you use any). They all should be on SSD: why else would you have one, if not to gain speed for the things you do frequently?
The number of writes may be limited, but a modern SSD is very good at wear leveling, so you shouldn't worry about it too much. The disk is there to be written to; if you don't use it for that, you might just as well use it as a paperweight and never even put it into your computer.
There is no storage device suited for swap space. Swap is slow, even on SSD. If you need to swap all the time, you're better off getting more RAM one way or another.
It may be different for swap space that's not used for swapping, but for suspend-to-disk scenarios. Naturally the faster the storage media used for that, the faster it will suspend and wake up again.
Personally, I put everything on SSD except the big, static data. A movie, for example, doesn't have to waste expensive space on SSD, as a HDD is more than fast enough to play it. It won't play any faster using SSD storage for it.
Like all storage media, SSD will fail at some point, whether you use it or not. You should consider them to be just as reliable as HDDs, which is not reliable at all, so you should make backups.