SSHD cloning - something special to keep in mind, compared to HDD?

**The question** is whether the fact the device is a hybrid disk has any (and what) importance when using dd or other such tools, or if all operations run the same as for a HDD. **The context** The device in question is a Seagate ST1000LM014. I used this command to make a backup before sending the laptop in for repairs (soundcard): dd if=/dev/sdb conv=sync,noerror bs=64K | gzip -c | split -b 2000m - ./sdb_backup.gz. Predictably the HP service guys formatted the drive, just because. I have no reason (yet) to suspect they swapped it. I restored the data: cat sdb_backup.gz.* | gunzip -c | dd of=/dev/sdb conv=sync,noerror bs=64K Now all that is visible from another Windows is the recovery partition, and gdisk -l /dev/sdb gives me:

Found valid GPT with protective MBR; using GPT.
Disk /dev/sdb: 1953525164 sectors, 931.5 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): {{I removed it}}
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 1953525130
Partitions will be aligned on 2048-sector boundaries
Total free space is 14851 sectors (7.3 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         1333247   650.0 MiB   2700  Basic data partition
   2         1333248         1865727   260.0 MiB   EF00  EFI system partition
   3         1865728         2127871   128.0 MiB   0C01  Microsoft reserved ...
   4         2127872      1907614565   908.6 GiB   0700  Basic data partition
   5      1907615744      1909415935   879.0 MiB   2700  
   6      1909415936      1953513471   21.0 GiB    0700  Basic data partition

gparted shows "unknown" for the type of the first 4 partitions. sdb4, at least, was supposed to be ntfs, but won't mount as such, or ntfs-3g - mount -r -t ntfs-3g /dev/sdb4 /media/myusername/sdb4 gives:

NTFS signature is missing.
Failed to mount '/dev/sdb4': Invalid argument
The device '/dev/sdb4' doesn't seem to have a valid NTFS.

But that's enough background, I think. I've tried many things for this error, failed to fix. I am not asking for a solution here.