I’m running TVHeadend on a Raspberry PI 3 with Rasbian. The recordings are written and read to/from a PIDRIVE with 250GB in size. This works like a charm. However, when reading large files, I’m experiencing a tremendous slow down at higher file positions (6GB and later). The read performance drops from almost maximum USB transfererate to values even lower than 100 bytes per second. It’s not a temperature thing, because it happens reproducibly, no matter if the drive is hot or cold. I can even start the transfere from the beginning of the file, immediatelly, and it reads again with maximum speed.
I’ve found other ppl reporting similar behaviour. However, no solution for it, yet. Using hdparm, there is an option mentioned, which might help fixing this for WD drives:
hdparm -m0 /dev/sda1
This turns of multi sector read and was found to be usefull. Unfortunatelly, the command doesn’t work on PIDRIVE. It says:
/dev/sda1:
setting multcount to 0
HDIO_SET_MULTCOUNT failed: Invalid argument
multcount = 16 (on)
Any other value between 1 and 16 doesn’t work either. I’ve tried this with hdparm V9.43.
The drive is running with ext4.
Any ideas?
UPDATE:
Surprisingly, I found that this only applies for a single file, yet. When copying the file, the copy works fine.
