I take VM live migration between VVOL datastores. It's very slow. I checked the logs and find that it will createNewVirtualVolume on the destination datastore. Then it will issue vaai xcopy, it will failed. Then it will call VASA method to copy data. I think the season of slow migrating is try VAAI. But I confused that from blogs, it saied
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XCOPY – With VVOLs, ESX will always try to use array based VVOLs copy mechanism defined using copyDiffsToVirtualVolume or CloneVirtualVolume primitives. If these are not supported, it will fall back to software copy.
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My quesiton is why it didn't issue "copyDiffsToVirtualVolume or CloneVirtualVolume primitives"? Does live storage migration not support it?