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"vxsnap refresh snapvol source=sourcevol" allows changing of the parent without dissociating the snapshot first

Created: 02 Aug 2012 • Updated: 20 Aug 2012 | 1 comment
Andrew_Law's picture
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Status: In Review

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?

 

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ajaykr's picture

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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