KB ID 0001452
When adding a ‘Backup Repository’ to Veeam you may see one of the following;
The file system on the specified volume does not support fast cloning. We recommend using ReFS volume formatted with 64 KB cluster size. Proceed anyway?
The specified ReFS volume is formatted with 4 KB cluster size. We recommend formatting the volume with 64 KB cluster size. Proceed anyway?
Without going into what ReFS is, think of it as the new NTFS. So that’s the format which you use when formatting the volume you want to use as a repository, the second error above will be seen if you did format the volume as ReFS but used the default 4 KB block size. This is what you need to do when creating the volume;
But there’s already data on the drive! Well tough, either accept and proceed, or move the data elsewhere and reformat. (At present there is no way to convert an NTFS volume to ReFS).