xcp sync errors - incomplete sync index and nfs3

[an0n]

Hi all,

a customer ran into an issue using XCP for NFS v 1.3-8 with the following output:

[root@FRVSM028 xcp]# ./xcp sync -id xcp_data 
XCP 1.3-8e0a9ec; (c) 2018 NetApp, Inc.; Licensed to user [None] until Tue Dec 11 21:04:14 2018

xcp: Index: {source: srcserver:/data, target: targetserver:/data_new} 


xcp: new sync for id 'xcp_data': WARNING: Incomplete sync index 'server:/xcp_data/sync/sync.index'.  Removing and trying again... 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.seld' (sync batch): nfs3 REMOVE 'file.seld' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.seld' (sync batch): nfs3 REMOVE 'file.seld' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.out' (sync batch): nfs3 REMOVE 'file.out' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.rsmout' (sync batch): nfs3 REMOVE 'file.rsmout' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.mode' (sync batch): nfs3 REMOVE 'file.mode' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.stat' (sync batch): nfs3 REMOVE 'file.stat' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.esav' (sync batch): nfs3 REMOVE 'file.esav' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.par' (sync batch): nfs3 REMOVE 'file.par' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder2/file1.err' (sync batch): nfs3 REMOVE 'file1.err' in 'targetserver:/data_new/folder2': nfs3 error 2: no such file or directory 
xcp: removeT1: WARNING: error removing 'targetserver:/data_new/folder1/file.DSP' (sync batch): nfs3 REMOVE 'file.DSP' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: diff 'xcp_data': Found 310 completed directories and 3 in progress 
xcp: sync 'xcp_data': 3,972 reviewed, 3,720 checked at source, 252 gone, 252 file.gone, 1 change, 2 modifications, 3,717 reindexed, 252 errors, 1.38 MiB in (518 KiB/s), 858 KiB out (315 KiB/s), 2s. 
xcp: sync 'xcp_data': Starting search pass for 5 modified/in-progress directories... 
xcp: sync phase 2: Rereading the 5 modified/in-progress directories... 
xcp: sync phase 2: WARNING: rescan 'srcserver:/data/folder2': nfs3 GETATTR 'srcserver:/data/folder2': nfs3 error 70: stale filehandle 
xcp: sync renames: WARNING: move2td targetserver:/data_new/folder1/file.par to targetserver:/data_new/folder1/_XCP_tmp: nfs3 RENAME 'file.par' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 
xcp: ERROR: nfs3 RENAME 'file.par' in 'targetserver:/data_new/folder1': nfs3 error 2: no such file or directory 

Syncs were successful before the failure, and no changes were made in the meantime.

I am aware of the stale filehandle which causes operations with folder2 to fail, and files that aren't on the target server can't be removed or renamed either. But are they the result of xcp's "Incomplete sync index"? How can that happen and how do I prevent this in future runs?

Thanks a lot in advance!