Public bug reported: Assuming we have configured everything correctly in OpenStack to use discard on Cinder block devices and we have checked that discard works, the wrong values for discard_granularity` and `discard_max_bytes` are reported to the VM's guest Operating System.
We can confirm this by checking the values on the host and the guest and see that they don't match: - `/sys/block/<dev>/queue/discard_max_bytes` - `/sys/block/<dev>/queue/discard_granularity`. The problem is that there is no code in Nova to set these values in libvirt, nor does Cinder or os-brick have any code to detect the right values to set. The libvirt fuctionality to set `discard_granularity` and `max_unmap_size` already exists: (https://bugzilla.redhat.com/show_bug.cgi?id=1408553. ** Affects: nova Importance: Undecided Status: New -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/2023210 Title: Wrong discard_granurality and discard_max_bytes reported in guest OS Status in OpenStack Compute (nova): New Bug description: Assuming we have configured everything correctly in OpenStack to use discard on Cinder block devices and we have checked that discard works, the wrong values for discard_granularity` and `discard_max_bytes` are reported to the VM's guest Operating System. We can confirm this by checking the values on the host and the guest and see that they don't match: - `/sys/block/<dev>/queue/discard_max_bytes` - `/sys/block/<dev>/queue/discard_granularity`. The problem is that there is no code in Nova to set these values in libvirt, nor does Cinder or os-brick have any code to detect the right values to set. The libvirt fuctionality to set `discard_granularity` and `max_unmap_size` already exists: (https://bugzilla.redhat.com/show_bug.cgi?id=1408553. To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/2023210/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : yahoo-eng-team@lists.launchpad.net Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
