copy offload failed

IKSOON · ‎2020-04-21

I have 2 questions.

1) Copy offload from Glance FlexVol to Cinder FlexVol was not working in my customer environment and my test environment.

- Test env: glance_vol and cinder_vol#1 are on the same node. And cinder_vol#2 is on the other node.

- Test#1: Creating nova with an image on glance_vol to cinder_vol#1 using copy offload failed. The Image was copied using regular downloading and registered in cache in cinder_vol#1.

- Test#2: Creating nova with the same image above to cinder_vol#2 using copy offload seemed successful. Cached image in cinder_vol#1 was copied to cinder_vol#2 using copy offload via cluster network.

- I configured copy offload tool following below guide

https://netapp-openstack-dev.github.io/openstack-docs/queens/glance/configuration/section_glance-enhanced-instance-config-NFS.html

- Is there anywhere in configuration I need to check?

2) Can copy offload tool be used with NFS v3?

- My customer wants to use copy offload tool with NFS v3 because of NFS v4’s long failover time.

- I tested the same tests above with NFS v3 and got the same result. Copy offload was not working on the first copy. But it worked the second time using NFS image cache on other cinder flexvol.

lseki · ‎2020-04-27

JinHak Kim from NetApp recently reported a similar issue, and shared the results in NetApp internal mailing list.

You might be talking about the same issue, but it's worth sharing his conclusions:

> To make long story short, through the internal test and communication, I concluded that copy-offload works both NFSv3 & NFSv4 protocol.

> When creating a VM, after downloading the glance image to cinder backend via copy-offload, the operation of converting the image format occurs.

> At this time, network IO happens. Don't misunderstand this for glance image regular download.

So the answers are the following:

1)

- Test#1: Creating nova with an image on glance_vol to cinder_vol#1 using copy offload failed. The Image was copied using regular downloading and registered in cache in cinder_vol#1.

Please check if copy offload really failed. In the cinder volume log, if the copy offload tool is returning 0 for the volume you're creating, copy offload is happening correctly in the 1st attempt as well.

It's probably taking longer because in the 1st attempt it requires image conversion.

2) Can copy offload tool be used with NFS v3?

Yes, you can.