I think this is 'blkdiscard --zero' option here. When we support just 'blkdiscard' (if the storage promises to return zeros on discarded blocks), it's a different option, no?
Yes, but since we're talking about the config value "zero_method" (see Bug 1367806), the option name is "blkdiscard". I will open a new BZ to track the second RFE you implied to, i.e when the user removes a disk with an intention to zero and discard it, and the underlying storage support discard_zeroes_data, then the disk is only discarded (and not wiped).
This depends on the scale's team ability to prove this method is safe.
Verified with the following code: ---------------------------------------- ovirt-engine-4.2.2.5-0.1.el7.noarch vdsm-4.20.23-1.el7ev.x86_64 Verified with the following scenario: ---------------------------------------- 1. Created a VM with 10G iscsi disk 2. Started the VM and wrote a 3G of data to the disk 3. Stop the VM 4. Remove the disk 5. Calculated the time that passes between the log message "Zero volume thread started for volume <volume_id>" and the log message "Zero volume <volume_id> task <task_id> completed" >>>>> 4 seconds passed. Moving to VERIFIED
This bugzilla is included in oVirt 4.2.2 release, published on March 28th 2018. Since the problem described in this bug report should be resolved in oVirt 4.2.2 release, it has been closed with a resolution of CURRENT RELEASE. If the solution does not work for you, please open a new bug report.