Restoring to a Target of Different Endianness Restoring to a Target of Different Endianness Depending on the strategy you used to back up the database, an extra step is required to restore a backup on a target system whose endianness (big-endian vs. little-endian) is different from the source system. For information about the endianness of supported platforms, see Platform Endianness. For External Backup or Cold Backup — convert a copied IRIS.DAT file as described in Using cvendian to Convert Between Big-endian and Little-endian Systems. For Online Backup or Concurrent External Backup — You cannot restore an IRIS.DAT file on a target system whose endianness is different from the source system. Instead, do the following: Use the procedure outlined in this section to restore on a system whose endianness is the same as the source. Shut down InterSystems IRIS or dismount the databases. Convert the database as described in Using cvendian to Convert Between Big-endian and Little-endian Systems. Copy the IRIS.DAT files to the target system. Use the procedure outlined in this section to restore on the target system with the converted databases, as described here for External Backup.