OpenNebula

Hi Drazen,

you can work around this issue with a hack-ish configuration in the file /etc/one/vmm_exec/vmm_exec_kvm.conf.

DISK = [ driver = "raw", cache = "writeback' discard='unmap" ]

OpenNebula does no sanitization of configuration input whatsoever. ( see: https://github.com/OpenNebula/one/blob/master/src/vmm/LibVirtDriverKVM.cc#L606 )

Hello,

The TRIM/DISCARD feature is supported by LVM, Ceph RBD and now with our StorPool block device driver too.

Please review this pull request [[https://github.com/OpenNebula/one/pull/65]]

We already have customers that are eager for this feature.

Regarding the Copyrights, this is small patch to enable an option to qemu-kvm, but if you are considering this as big one I or our company are ready to start a procedure of signing a (Company) Contributor License Agreement. In this case please point us to the right document (Company vs Personal one) to proceed.

Kind Regards,
Anton Todorov
StorPool

Hi,

I just want to add that trim/discard IS supported by virtio-scsi but not by old virtio-blk driver.
As a consequence, to be able to use vistio-iscsi inside opennebula, feature #3053 has to be implemented.

Regards,

Laurent

Hi,

I can confirm that it is working in 4.14.0 with virtio-scsi with following options in Advanced Options of VM template/storage tab set:

Device Prefix: sd
Discard: unmap
IO: native
Cache: none

Here is the result inside the VM

[root@localhost ~]# lsblk -D
NAME   DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
sda           0        4K       1G         0
└─sda1        0        4K       1G         0
sr0           0        0B       0B         0

IMO feature #3053 will improve virtio-scsi performance (is it equivalent of virtio-bkl-dataplane ?).

Here is example in action: after system update and followed fstrim here are the stats shown on storpool:

[root@s07 ]# storpool volume usedSpace
-----------------------------------------------------------------------
| volume               |       size | repl. |     stored |       used |
-----------------------------------------------------------------------
| one-img-0            |      10 GB |     3 |       0  B |     912 MB |
| one-img-0-12-0       |      10 GB |     3 |     587 MB |     1.3 GB |
-----------------------------------------------------------------------

[root@s07 ]# storpool volume usedSpace
-----------------------------------------------------------------------
| volume               |       size | repl. |     stored |       used |
-----------------------------------------------------------------------
| one-img-0            |      10 GB |     3 |       0  B |     912 MB |
| one-img-0-12-0       |      10 GB |     3 |     402 MB |     1.1 GB |
-----------------------------------------------------------------------

[root@localhost ~]# df -m
Filesystem     1M-blocks  Used Available Use% Mounted on
/dev/sda1          10228  1133      9096  12% /
devtmpfs             354     0       354   0% /dev
tmpfs                371     0       371   0% /dev/shm
tmpfs                371    10       362   3% /run
tmpfs                371     0       371   0% /sys/fs/cgroup

Kind Regards,
Anton

Support for <controller type='scsi' index='0' model='virtio-scsi'></controller> must be implemented in the core.

Please consider adding option to configure multi-queues on virtio-scsi

hints: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Virtualization_Tuning_and_Optimization_Guide/sect-Virtualization_Tuning_Optimization_Guide-BlockIO-Techniques.html#sect-Virtualization_Tuning_Optimization_Guide-BlockIO-Multi-queue_virtio-scsi

<controller type='scsi' index='0' model='virtio-scsi'>
   <driver queues='N' />
</controller>