Swap on ZFS

[Rolf Nielsen]

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On 2014-05-06 21:21, David Noel wrote:
> Is swap on ZFS still ill-advised? All the forum, list, and blog
> posts I find say it's a no-go. Is this still the case? The idea
> behind it not working is that ZFS needs memory to write to disk, so
> when you need to swap (are low on memory) ZFS won't be able to
> write.
> 
> I found some talk of having a tunable added as a workaround that
> would reserve a certain amount of memory for ZFS so this wouldn't
> be a problem, but have no idea if anyone's made any progress
> towards implementing it.

Just out of curiosity, why do you want it?

To get swap on ZFS, you first need to create a ZFS filesystem on one
or more devices, then you create a dedicated volume inside that
filesystem and use that dedicated volume as swap. To me that seems to
add unnecessary complexity, similar to using a file backed md device
as swap. Please don't take this as criticism; you may very well have
good reasons for wanting to do this. I'm just curious about those reasons.

Rolf Nielsen

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