To create an extent pool:
mkdir "${EXTENT_POOL_NAME}"
echo "${EXTENT_TABLE_PATH}" > "${EXTENT_POOL_NAME}/ext_tbl_path"
echo "${EXTENT_FREE_LIST_INDEX_PATH}" > "${EXTENT_POOL_NAME}/ext_fri_path"
echo "${EXTENT_DATA_PATH}" > "${EXTENT_POOL_NAME}/ext_dat_path"
echo "${EXTENT_VOL_NUM}" > "${EXTENT_POOL_NAME}/vol_num"
echo "1" > "${EXTENT_POOL_NAME}/enable"