That’s a good call out. I’ve never used ZFS on root. Been a ZFS user on Linux since the FUSE days but it has never seemed particular well suited (O_DIRECT support came late, ARC/page cache redundancy, etc). I can’t guarantee a consistent enough workload to optimize ZFS for and I don’t feel like it’s general purpose enough. Large object storage though? I’m sitting on a PB of ZFS.
replyzswap indeed is the real magic almost silver bullet nowadays. Device backed swap is often not needed anymore and it solves a lot of the issues with freezing under memory pressure, though it may not be ideal for servers.
replyAnd if I have a separate otherwise unused ssd then using a swap partition simply is easier than creating a file system for it and mounting it somewhere. Block level backups also are easier.
What would be nice about swap files is if they could dynamically grow and shrink without a special setup.
Way too many variables on Linux for a one size fits all.
It also doesn't sound like a particularly good idea on BTRFS, judging by the linked documentation:
replyAnd since you should probably be running a modern CoW filesystem then you probably shouldn't be using swapfiles ... is the conclusion I arrived at anyway. Either install multiple times more RAM than you need and enable zswap or else set aside a swap partition as has always been done.
replyTruth be told—- I don’t use swap and set `vm.swappiness=0` but in these difficult times, swap may be the hero we need.
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