Hi guys I just wanted to let everyone know that as of r249921
TRIM on ZFS is enabled by default unless you explicitly disable
it using vfs.zfs.trim.enabled in loader.conf.
Delete support for CAM SCSI now includes supporting ATA TRIM on
SCSI controllers as long as the controller supports ata_pass16
(one notable controller set which doesn't is areca).
This means controllers such as mpt, which don't natively support
SCSI UNMAP to ATA TRIM translation in FW, now gain BIO_DELETE
support via ATA TRIM if your using SATA disks.
The way the default delete_method is chosen has also changed from
a try and fail methodology to query the device details via VPD
and ATA IDENTIFY.
Delete method choice in CAM SCSI has also changed to prefer ATA
TRIM if available as testing has show that even those controllers
that support UNMAP to TRIM translation it is up to 20% slower than
using ATA TRIM via pass16. This can still be overridden using
the kern.cam.da.X.delete_method.
I'd really appreciate any feedback people have, even if that's just
confirming your running with ZFS TRIM and haven't had any issues,
as I'm looking to MFC to stable soon.
FYI: We've been running it for over 9 months now on hundreds of
machines without any real issues.
Regards
Steve
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