lockup during zfs destroy

[Gary Palmer]

On Wed, Oct 04, 2017 at 09:15:27AM -0700, javocado wrote:
> My questions:
> 
> - is this what it appears to be, a memory exhaustion?
> - if so, why isn't swap utilized?

Kernel memory generally isn't pushed to swap as it could lead to deadlock
situations way too easily.

> - how would I configure my way past this hurdle?
> - a filesystem has a DELETE_QUEUE ... does the zpool itself have a destroy
> queue of some    kind?  I am trying to see if I can see the zpool working
> and how far along it is, but I do not know what to query with zdb

Yes, it does, I believe behind the feature at async_destroy flag on
the pool.  "zpool get feature at async_destroy" to see the enabled
status.  Not sure if you can query the queue to see how it is
progressing.  I haven't destroyed any pools, but with snapshots
you can check the free space on the pool using "zpool list"
and it gradully increases in the background.

Regards,

Gary