Making gmirror metadata cooperate with gpt metadata

[Paul Mather]

On Feb 8, 2021, at 1:36 PM, Kevin P. Neal <kpn at neutralgood.org> wrote:

> On Sun, Feb 07, 2021 at 05:55:58PM -0500, Paul Mather wrote:

>> To be honest, I don't remember what it does because I only use gmirror
>> for swap nowadays, but I have a sneaking suspicion from memory that it was
> 
> Is this safe? I thought that gmirror could attempt to allocate memory, so in
> a low memory situation where you are swapping it could deadlock.


Actually, I always remember the flipside: there was a time when folks said not to swap to ZFS volumes because memory pressure from ARC could lead to increased paging out to swap that could lead to the sort of deadlock you mention due to even more memory pressure by ZFS.

I can't remember hearing any caveats about swapping to gmirror.


> Or did that only apply when using encryption?


I've never had an issue swapping to a gmirror'd swap partion, encrypted or otherwise.  I build my own packages via Poudriere, which usually guarantees giving swap a good workout. :-)

Cheers,

Paul.