I also attached a quick debug patch for capturing some more info.
This is, what I am getting now with both patches applied in order:
[ +0.000690] scsi 6:0:0:0: Direct-Access Seagate Backup+ Hub BK
D781 PQ: 0 ANSI: 6
[ +0.001009] sd 6:0:0:0: Attached scsi generic sg3 type 0
[ +0.000199] sd 6:0:0:0: [sdc] Spinning up disk...
[ +0.982900] ..
[ +0.300907] ..........ready
[Mär23 00:19] sd 6:0:0:0: [sdc] sd_read_capacity: rc10_first 0,
rc16_first: 1
[ +0.000068] sd 6:0:0:0: [sdc] read_capacity_16: result 0, retries 2
[ +0.000002] sd 6:0:0:0: [sdc] read_capacity_16: lbs 512, pbs 512, last
LBA 3a3812aae
[ +0.000236] sd 6:0:0:0: [sdc] 15628053167 512-byte logical blocks:
(8.00 TB/7.28 TiB)
[ +0.070974] sd 6:0:0:0: [sdc] Write Protect is off
[ +0.000002] sd 6:0:0:0: [sdc] Mode Sense: 4f 00 00 00
[ +0.000153] sd 6:0:0:0: [sdc] Write cache: enabled, read cache:
enabled, doesn't support DPO or FUA
[ +0.000200] sd 6:0:0:0: [sdc] Preferred minimum I/O size 512 bytes
[ +0.000001] sd 6:0:0:0: [sdc] Optimal transfer size 33553920 bytes
[ +0.020349] sd 6:0:0:0: [sdc] sd_read_capacity: rc10_first 0,
rc16_first: 1
[ +0.000094] sd 6:0:0:0: [sdc] read_capacity_16: result 0, retries 2
[ +0.000002] sd 6:0:0:0: [sdc] read_capacity_16: lbs 512, pbs 4096,
last LBA 3a3812aae
[ +0.021930] sd 6:0:0:0: [sdc] sd_read_capacity: rc10_first 0,
rc16_first: 1
[ +0.000079] sd 6:0:0:0: [sdc] read_capacity_16: result 0, retries 2
[ +0.000002] sd 6:0:0:0: [sdc] read_capacity_16: lbs 512, pbs 4096,
last LBA 3a3812aae
[ +0.000567] sd 6:0:0:0: [sdc] Attached SCSI disk
