I've split my SDcard to two part, one of them can not be mounted and got some error message, here are the message:

$ sudo fdisk -l /dev/sdd
[sudo] password for gina:
Disk /dev/sdd: 7.4 GiB, 7969177600 bytes, 15564800 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
Disklabel type: dos
Disk identifier: 0x00000000

所用裝置 可開機 Start 結束 磁區 Size Id 類型
/dev/sdd1 8192 24575 16384 8M c W95 FAT32 (LBA)
/dev/sdd2 24576 15564799 15540224 7.4G 83 Linux

$ sudo mount -t ext4 /dev/sdd2 tmp/p2
mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
missing codepage or helper program, or other error

In some cases useful info is found in syslog - try
dmesg | tail or so.

$ dmesg |tail
[949945.558260] Buffer I/O error on dev sdd2, logical block 1, lost async page write
[949950.310258] sd 7:0:0:0: [sdd] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[949950.310266] sd 7:0:0:0: [sdd] tag#0 Sense Key : Unit Attention [current]
[949950.310272] sd 7:0:0:0: [sdd] tag#0 Add. Sense: Not ready to ready change, medium may have changed
[949950.310278] sd 7:0:0:0: [sdd] tag#0 CDB: Write(10) 2a 00 00 00 6f e0 00 00 18 00
[949950.310282] print_req_error: I/O error, dev sdd, sector 28640
[949950.310293] Buffer I/O error on dev sdd2, logical block 508, lost async page write
[949950.310313] Buffer I/O error on dev sdd2, logical block 509, lost async page write
[949950.310319] Buffer I/O error on dev sdd2, logical block 510, lost async page write
[950135.024267] EXT4-fs (sdd2): VFS: Can't find ext4 filesystem


Anyone know what's the problem and how to fix it?
Thank you very much!!

1. tmp/p2 exists! I've create it in my locol directory
2. I've tryed mount /dev/sdd2 tmp/p2, the result is the same
Any suggestion?

How did you 'split' your card?
Did you create new partitions(?)
Did you put new filesystems onto the SD cards new partitions(?).

Gparted magic works. Just use gParted to create your partitions. as it is you Might have to redo your partition table, to reestablish your medium, and it will wipe everything off the medium in the process.

before that, you can make sure you formatted it ext4, if not, then format it ext4. mount without the -t ext4

1.
I created my partition before with $sudo fdisk /dev/sdd
enter command: n p 1 8192 24575 t c n p 2 24576 p w

2
I've try GParted, when I deleted partition, Libparted error show input/output error.
The sdd2 partition shows message below:
e2label: No such file or directory while trying to open /dev/sdd2
Couldn't find valid filesystem superblock.

tune2fs 1.42.13 (17-May-2015)

tune2fs: No such file or directory while trying to open /dev/sdd2
Couldn't find valid filesystem superblock.

Couldn't find valid filesystem superblock.

dumpe2fs 1.42.13 (17-May-2015)
dumpe2fs: No such file or directory while trying to open /dev/sdd2

3.
I've mount it again, message shows below:
$ sudo mount /dev/sdd2 /mnt/p2
mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
missing codepage or helper program, or other error

In some cases useful info is found in syslog - try
dmesg | tail or so.
$ dmesg |tail
[ 1166.961825] EXT4-fs (sdd2): no journal found

I do not do fdisk, gfdisk, yes, gparted, yes, you might be getting your blocks off so it's erroring out, that is why I do not use fdisk.

I think this article may help. It specifically refers to the file system type issue.

https://www.fosslinux.com/3822/sd-ca...-is-a-fix.htm/

As already asked...

A partition is just a container for a filesystem. While fdisk creates the container it does not create the filesystem. To create an ext4 filesystem on sdd2

Always very the correct device ID before executing the mkfs command.

Thanks for everyone's suggestion!
I've change the card reader, and it's all work!