# fdisk -l reports 1953525168 sectors of 512 bytes

Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

# ...but running badblocks with this amount as suggested reports a bad block at **block 1953525168**:

$ badblocks -b 512 -vws -o "badblocks_1953525168.txt" /dev/sda 1953525168 1953525168
Checking for bad blocks in read-write mode
From block 1953525168 to 1953525168
Testing with pattern 0xaa: Weird value (4294967295) in do_writerrors)
done
Reading and comparing: done
Testing with pattern 0x55: Weird value (4294967295) in do_writerrors)
done
Reading and comparing: done
Testing with pattern 0xff: Weird value (4294967295) in do_writerrors)
done
Reading and comparing: done
Testing with pattern 0x00: Weird value (4294967295) in do_writerrors)
done
Reading and comparing: done
Pass completed, 1 bad blocks found. (1/0/0 errors)

# Running with last block +1 gives the expected seekrs error and reports a bad block at **block 1953525170** (i.e. last block +2)

$ badblocks -b 512 -vws -o "badblocks_1953525169.txt" /dev/sda 1953525169 1953525169
Checking for bad blocks in read-write mode
From block 1953525169 to 1953525169
Testing with pattern 0xaa: badblocks: Invalid argument during seekrs)
done
Reading and comparing: badblocks: Invalid argument during seekrs)
done
Testing with pattern 0x55: badblocks: Invalid argument during seekrs)
done
Reading and comparing: badblocks: Invalid argument during seekrs)
done
Testing with pattern 0xff: badblocks: Invalid argument during seekrs)
done
Reading and comparing: badblocks: Invalid argument during seekrs)
done
Testing with pattern 0x00: badblocks: Invalid argument during seekrs)
done
Reading and comparing: badblocks: Invalid argument during seekrs)
done
Pass completed, 1 bad blocks found. (0/0/1 errors)

# Running with last block -1 makes everything function as expected, with **no reported bad blocks**

$ badblocks -b 512 -vws -o "badblocks_1953525167.txt" /dev/sda 1953525167 1953525167
Checking for bad blocks in read-write mode
From block 1953525167 to 1953525167
Testing with pattern 0xaa: done
Reading and comparing: done
Testing with pattern 0x55: done
Reading and comparing: done
Testing with pattern 0xff: done
Reading and comparing: done
Testing with pattern 0x00: done
Reading and comparing: done
Pass completed, 0 bad blocks found. (0/0/0 errors)