DiskStoreBackup getBackupForDiskStore(DiskStoreImpl diskStore) {
    return backupByDiskStore.get(diskStore);
  }
Start the backup process. This is the second step of the backup process. In this method, we
define the data we're backing up by copying the init file and rolling to the next file. After
this method returns operations can proceed as normal, except that we don't remove oplogs.
geode-core/src/main/java/org/apache/geode/internal/cache/backup/BackupTask.java