"vxsnap refresh snapvol source=sourcevol" allows changing of the parent without dissociating the snapshot first
I found the following behaviour of vxsnap refresh.
rhel6vm1# vxsnap -g tdg refresh volisnap source=volfmr3 sync=on <<< use volfmr3 as parent
rhel6vm1# vxsnap -g tdg -nBv print
NAME DG OBJTYPE SNAPTYPE PARENT PARENTDG SNAPDATE CHANGED_DATA SYNCED_DATA
volfmr3 tdg vol - - - - - - - 204800 (100%)
volisnap tdg vol fullinst volfmr3 tdg 2012/08/01 12:33 0 (0%) 204800 (100%)
rhel6vm1# vxsnap -g tdg refresh volisnap source=volfmr3x sync=off <<< switching to volfmr3x as parent
There is no warning from VxVM regarding the existing snapshot association.
rhel6vm1# vxsnap -g tdg -nBv print
NAME DG OBJTYPE SNAPTYPE PARENT PARENTDG SNAPDATE CHANGED_DATA SYNCED_DATA
volfmr3x tdg vol - - - - - - - 204800 (100%)
volisnap tdg vol fullinst volfmr3x tdg 2012/08/01 12:33 0 (0%) 0 (0%)
My worry is that one typing mistake may cost the whole snapshot. Should vxsnap first requests to dissociate the snapshot from the existing parent before allowing it to be associated with another parent?
Comments 1 Comment • Jump to latest comment
Andrew, thanks for the post. As discussed, it is a valid concern to allow refreshing a snapshot from different source than current source.
This facility was merely put for test purposes (refresh across different snapshot hierarchies) and shouldn't be a default behavior. So we have planned to prevent this behavior unless user explicitly specifies force option (-f). To that effect we opened an incident to track this issue (2952553) and have fixed the issue in the internal branch. We are working on getting the fixes available in the next patch-releases for the major release versions.
Thanks.
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