Bug 1325843

+++ This bug was initially created as a clone of Bug #1322214 +++

+++ This bug was initially created as a clone of Bug #1314421 +++

Description of problem:
In a oVirt-Gluster hyperconverged environment, adding disk to VM from a glusterfs storage pool fails when glusterfs is running in posix/directio mode

The gluster volume is configured to run in directIO mode by adding 

option o-direct on 

in the /var/lib/glusterd/vols/gl_01/*.vol files. Example below

volume gl_01-posix
    type storage/posix
    option o-direct on
    option brick-gid 36
    option brick-uid 36
    option volume-id c131155a-d40c-4d9e-b056-26c61b924c26
    option directory /bricks/b01/g
end-volume

When the option is removed and the volume is restarted, disks can be added to the VM from the glusterfs pool.


Version-Release number of selected component (if applicable):

ovirt version is 3.6

glusterfs-client-xlators-3.7.5-11.el7rhgs.x86_64
glusterfs-cli-3.7.5-11.el7rhgs.x86_64
glusterfs-libs-3.7.5-11.el7rhgs.x86_64
glusterfs-3.7.5-11.el7rhgs.x86_64
glusterfs-api-3.7.5-11.el7rhgs.x86_64
glusterfs-fuse-3.7.5-11.el7rhgs.x86_64
glusterfs-server-3.7.5-11.el7rhgs.x86_64



How reproducible:
Easily reproducible

Steps to Reproduce:
1. Create a GlusterFS storage pool in an oVirt environment 
2. Configure GlusterFS in a posix/directIO mode
3. Create a new VM or add disk to an existing VM. The add disk part fails

Actual results:


Expected results:


Additional info:

--- Additional comment from Krutika Dhananjay on 2016-03-17 08:11:14 EDT ---

Hi Sanjay,

In light of the recent discussion we had wrt direct-io behavior on a mail thread, I have the following question:

Assuming the 'cache=none' command line option implies that the vm image files will all be opened with O_DIRECT flag (which means that the write buffers will already be aligned with the "sector size of the underlying block device", the only layer in the combined client-server stack that could prevent us from achieving o-direct-like behavior because of caching would be the write-behind translator.

Therefore, I am wondering if it is sufficient to enable 'performance.strict-o-direct' to achieve the behavior you expect to see with o-direct?

-Krutika

--- Additional comment from Sanjay Rao on 2016-03-17 08:20:02 EDT ---

I have tested with different options. The only option that enabled true directIO on the glusterfs server was the posix setting.

I can verify again with the performance.strict-o-direct with the recent glusterfs version (glusterfs-server-3.7.5-18.33) installed on my system just to be sure.

--- Additional comment from Vijay Bellur on 2016-03-29 23:27:59 EDT ---

REVIEW: http://review.gluster.org/13846 (features/shard: Make o-direct writes work with sharding) posted (#1) for review on master by Krutika Dhananjay (kdhananj)

--- Additional comment from Vijay Bellur on 2016-04-06 05:50:14 EDT ---

REVIEW: http://review.gluster.org/13846 (features/shard: Make o-direct writes work with sharding) posted (#2) for review on master by Krutika Dhananjay (kdhananj)

--- Additional comment from Vijay Bellur on 2016-04-11 02:01:27 EDT ---

REVIEW: http://review.gluster.org/13846 (features/shard: Make o-direct writes work with sharding) posted (#3) for review on master by Krutika Dhananjay (kdhananj)

--- Additional comment from Vijay Bellur on 2016-04-11 05:07:14 EDT ---

REVIEW: http://review.gluster.org/13846 (features/shard: Make o-direct writes work with sharding) posted (#4) for review on master by Krutika Dhananjay (kdhananj)