// case 8: truncate to 2 blocks
    // the original 2.5 blocks are in snapshot. the block truncated is not
    // in snapshot. diff should be -0.5 block
// case 8: truncate to 2 blocks
    // the original 2.5 blocks are in snapshot. the block truncated is not
    // in snapshot. diff should be -0.5 block | TestTruncateQuotaUpdate.java