Having had my Humax HDR-1000S since October 2013, I recently had the problem with pause (time shift recording - TSR), which is manifest by not being able to pause a live broadcast, and getting the message:
"The function does not work while retrieving data for time shift buffer.
Try again in a few minutes."
I have now recovered from this, having bought a new hard drive, and my conlusion was that it was caused by a Humax software write error when shutting down - as I had tried power cycling due to recent problems with iPlayer and YouTube.
I took the disk out of the Humax box and put it into a caddy connected by USB to my Linux laptop.
gparted shows humax disk has 3 partitions, all using Linux filesystem ext3, with 2.49 MB unallocated.
Old (original) humax disk is /dev/sde
sde1 1G
sde2 920.5G
sde3 10G
in which sde2 has the recordings.
So I mounted sde2 (to /mnt/old1tb) and saw it had 4 directories:
'My Music', 'My Photo', 'My Video', Tsr
but also got an error message for Tsr:
ls: cannot access 'Tsr': Structure needs cleaning
I also checked 'My Video' folder and saw all our recordings (3 files per recording) (using 67% of 1TB).
A few files there also reported error, e.g.:
ls: cannot access 'old1tb/My Video/.2_20200807_1802.hjm': Structure needs cleaning
but these seemed to be old and not the usual name format (which takes the actual name of the programme being recorded).
At this point, you could take a backup of the disk (or even a clone) just for safety, and then use gparted to check and fix the filesystem, and hopefully preserve your recordings.
Instead, I took this opportunity to upgrade from 1 TB disk to a new 2 TB disk.
I used new disk: (Seagate SkyHawk 2TB SATA-3 3.5 inch, 5900RPM, 64MB Cache)
and a caddy for it and the old disk:
Fideco HDD docking station
I formatted the new disk in the Humax box, confirmed it solved the pause/TSR problem, then took it out again and put it in the caddy above, along with the old disk.
I then mounted the new disk as new2tb, and copied the files from old "My Video" to the new "My Video". This took some hours. It would probably have been quicker to copy the partition as a whole, then fix copied errors in the new disk, but it seemed more likely to work cleanly doing the copy of files.
I then unmounted and tried the new disk in the Humax and all seemed fine. Old recordings were available and worked - happy wife = happy life 
.
While I had the old disk in the caddy, I thought I might as well use gparted to fix the file system errors. I found that this removed the corrupted Tsr directory, so re-created it. I did not use the disk in the Humax box again though.
