extremely slow disk I/O after updating to 12.0

[Robert Schulze]

Hi,

Am 03.07.19 um 13:34 schrieb David Demelier:
> Hello folks,
> 
> I've upgraded one of my servers to 12.0-RELEASE. Now I'm having
> extremely slow performances regarding I/O writes.

we have seen a drop in I/O performance beginning with 11.2-RELEASE.
Try disabling scattered ABD:

sysctl vfs.zfs.abd_scatter_enabled=0

regards,
Robert Schulze