https://knowledgebase.macrium.com/display/KNOW/Backup+aborted+-+Write+operation+failed+-+The+request+could+not+be+performed+because+of+an+IO+device+error
https://knowledgebase.macrium.com/display/KNOW7/Error+0x80070510+when+deleting+backup+files
Turns out this is Macrium backup which I’m using.
Bottom drive-BuffaloB 2nd from Bottom-VMware 2nd from top-DPC Top-MainPC