I noticed the swap file went missing after the latest update to Sierra (10.12.5) though swap seems to be working.

Mach Virtual Memory Statistics: (page size of 4096 bytes)
Pages free:                             2152219.
Pages active:                            898204.
Pages inactive:                          276296.
Pages speculative:                       437656.
Pages throttled:                              0.
Pages wired down:                        427700.
Pages purgeable:                         133196.
"Translation faults":                  67396051.
Pages copy-on-write:                    6410771.
Pages zero filled:                     30858807.
Pages reactivated:                           31.
Pages purged:                             42928.
File-backed pages:                       715857.
Anonymous pages:                         896299.
Pages stored in compressor:                   0.
Pages occupied by compressor:                 0.
Decompressions:                               0.
Compressions:                                 0.
Pageins:                                 414848.
Pageouts:                                     0.
Swapins:                                      0.
Swapouts:                                     0.

Has anyone else seen this behavior and can confirm it’s intended and/or harmless?


In previous versions of OS X I always had at least one swapfile. That never went 'away'. Regardless of how much RAM was available.

But since Mavericks the memory management improved steadily (including zram-like vm-compression) and on the latest macOS after a fresh reboot I also do not see a swapfile. It gets then created as needed.

Only if you have low amounts of RAM in the machine and never see such a file created is there a reason for concern.

If you open a few apps and then Safari with a few tabs filled you shall see those files again.

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Swapfiles, by their very nature, are ephemeral, and are created & destroyed at the whim of the OS.

Perhaps the update process deleted the swapfile as it would have contained outdated, and thus useless data, especially if it contained data germane only to the previous version of the OS.

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