Here is gnu parted output with mdadm installed and configured.
mint@mint ~ $ sudo parted
GNU Parted 2.3
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) exit                                                             
  align-check TYPE N                        check partition N for TYPE(min|opt)
        alignment
  check NUMBER                             do a simple check on the file system
  cp [FROM-DEVICE] FROM-NUMBER TO-NUMBER   copy file system to another partition
  help [COMMAND]                           print general help, or help on
        COMMAND
  mklabel,mktable LABEL-TYPE               create a new disklabel (partition
        table)
  mkfs NUMBER FS-TYPE                      make a FS-TYPE file system on
        partition NUMBER
  mkpart PART-TYPE [FS-TYPE] START END     make a partition
  mkpartfs PART-TYPE FS-TYPE START END     make a partition with a file system
  resizepart NUMBER END                    resize partition NUMBER
  move NUMBER START END                    move partition NUMBER
  name NUMBER NAME                         name partition NUMBER as NAME
  print [devices|free|list,all|NUMBER]     display the partition table,
        available devices, free space, all found partitions, or a particular
        partition
  quit                                     exit program
  rescue START END                         rescue a lost partition near START
        and END
  resize NUMBER START END                  resize partition NUMBER and its file
        system
  rm NUMBER                                delete partition NUMBER
  select DEVICE                            choose the device to edit
  set NUMBER FLAG STATE                    change the FLAG on partition NUMBER
  toggle [NUMBER [FLAG]]                   toggle the state of FLAG on partition
        NUMBER
  unit UNIT                                set the default unit to UNIT
  version                                  display the version number and
        copyright information of GNU Parted
(parted) print                                                            
Error: Invalid argument during seek for read on /dev/sda                  
Retry/Ignore/Cancel? i                                                    
Error: The backup GPT table is corrupt, but the primary appears OK, so that will
be used.
OK/Cancel? ok                                                             
Backtrace has 8 calls on stack:
  8: /lib/x86_64-linux-gnu/libparted.so.0(ped_assert+0x31) [0x7f0fe89a34b1]
  7: /lib/x86_64-linux-gnu/libparted.so.0(+0x3f5f6) [0x7f0fe89d35f6]
  6: /lib/x86_64-linux-gnu/libparted.so.0(ped_disk_new+0x49) [0x7f0fe89a8f99]
  5: parted() [0x406dff]
  4: parted(interactive_mode+0x101) [0x40db71]
  3: parted(main+0x153d) [0x4065bd]
  2: /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5) [0x7f0fe8181ec5]
  1: parted() [0x406617]
                                                                          

You found a bug in GNU Parted! Here's what you have to do:

Don't panic! The bug has most likely not affected any of your data.
Help us to fix this bug by doing the following:

Check whether the bug has already been fixed by checking
the last version of GNU Parted that you can find at:

	http://ftp.gnu.org/gnu/parted/

Please check this version prior to bug reporting.

If this has not been fixed yet or if you don't know how to check,
please visit the GNU Parted website:

	http://www.gnu.org/software/parted

for further information.

Your report should contain the version of this release (2.3)
along with the error message below, the output of

	parted DEVICE unit co print unit s print

and the following history of commands you entered.
Also include any additional information about your setup you
consider important.

Assertion (last_usable <= disk->dev->length) at
../../../libparted/labels/gpt.c:994 in function _parse_header() failed.