Why is my server using all my Swap but I have RAM to spare?
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"hey, this memory page is never used and this file block is used a lot, so I'm going to put the memory page on disk and the file block in memory and everything will be faster."
except when not, like when I just copied a multi GB file, it was cached in RAM to be not read again for long, but at least half of my running programs are swapped out. Additionally if swap is o SSD, it has put totally unnecessary wear into it by doing this
That's why you can adjust swappiness, or designate a different high-endurance storage device for it.
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1gb swap is way too small...
I usually setup swap to be 2x the total ram size. So, 32gb swap in your case.
Nothing wrong here, seems normal. With such little swap.
Actually Linux kernel works better with swap, the more the better. It will lalso perform better than zero swap. Counterintuitive indeed, but that's how it works.
If you don't want swap, use zram.
+1 for
zramswap, especially if you're tight on RAM but have a few CPU cycles to spare. -
And how does cache space figure in to this? I have a server with 64GB of RAM, of which 46GB is being used by system cache, but I only have 450MB of free memory and 140MB of free swap. The only 'volatile' service I have running is slapd which can run in bursts of activity, otherwise the only thing of consequence running is webmin and some VMs which collectively can use up to 24GB (though they actually use about half that) but there's no reason those should hit swap space. I just don't get why the swap space is being run dry here.
That's how Linux manages it memory, it will use free memory as file cache till it needs it. Then free up memory for process use.
If your only half using the memory for actual services, you may want to reduce it.
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