clone target can be bigger (EMC® Solutions Enabler Symmetrix® TimeFinder® Family CLI Version 7.1)  Copying from a source device to a larger target device Clone source and target devices no longer have the requirement to be the same size.Now the size of a clone target device can be larger than the source device. Thissupport requires the following SYMCLI environment variable be set:SYMCLI_CLONE_LARGER_TGT = ENABLEDLimitations — The following limitations apply:◆ Restore is not allowed.◆ Full copy support only; cannot use -differential.◆ Concatenated metadevices are not supported.◆ When using this feature on striped metadevices you have to preserve themetageometry. That is, the source and target devices should contain the samenumber of metamembers. However, the target device members can be larger thanthe source device members.
while selecting clone tgt or BCV devices can we choose a device which is of different in size may be a bigger vol or a smaller volume.. Is there any documents available for the best practices.  
Clones/BCV