Trouble mounting 5Tb external USB device

[slackline]

Hi,

I purchased a Seagate Backup Plus 5 TB USB 3.0 Portable 2.5" drive as I've recently maxed out the 1TB drive I have connected to my RPi2 running ArchLinuxARM and serving up music around the home (thanks to snapcast).

I've formtated the drive from the default Micro$oft with ext4 on my main desktop/server (running Gentoo) without any problem. I purposefully omitted reserving space for root on the device when doing so using the '-m 0' option...

$this->bbcode_second_pass_code('', '
mkfs.ext4 -m 0 /dev/sdg1
')

...and once complete used rsync to copy all my ripped music and video to the Seagate drive before plugging it into the RPi2.

The RPi2 detects the device and purports to mount it but I can not read anything from it nor is it detected by df...

$this->bbcode_second_pass_code('', '
dmesg | grep sdb -B5 -A5
[ 6.818812] systemd[1]: Set hostname to <alarmpi>.
[ 7.138564] uart-pl011 3f201000.serial: no DMA platform data
[ 7.314785] systemd[1]: File /usr/lib/systemd/system/systemd-journald.service:35 configures an IP firewall (IPAddressDeny=any), but the local system does not support BPF/cgroup based firewalling.
[ 7.340062] systemd[1]: Proceeding WITHOUT firewalling in effect! (This warning is only shown for the first loaded unit using IP firewalling.)
[ 7.437703] scsi 1:0:0:0: Direct-Access Seagate BUP SL 0304 PQ: 0 ANSI: 6
[ 7.454293] sd 1:0:0:0: [sdb] Spinning up disk...
[ 7.775111] systemd[1]: Set up automount mnt-seagate\x2d5tb.automount.
[ 7.787824] systemd[1]: Set up automount mnt-backup\x2dvideo.automount.
[ 7.798924] systemd[1]: Reached target Remote File Systems.
[ 7.809832] systemd[1]: Set up automount mnt-backup\x2dpics.automount.
[ 7.821316] systemd[1]: Set up automount Arbitrary Executable File Formats File System Automount Point.
--
[ 9.516523] .
[ 10.556508] .
[ 11.596497] .
[ 12.636494] .
[ 12.636861] ready
[ 12.641384] sd 1:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16).
[ 12.651628] sd 1:0:0:0: [sdb] 9767541167 512-byte logical blocks: (5.00 TB/4.55 TiB)
[ 12.664365] sd 1:0:0:0: [sdb] 2048-byte physical blocks
[ 12.737473] sd 1:0:0:0: [sdb] Write Protect is off
[ 12.744906] sd 1:0:0:0: [sdb] Mode Sense: 4f 00 00 00
[ 12.745512] sd 1:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 12.761056] sd 1:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16).
[ 12.863681] sdb: sdb1
[ 12.870411] sd 1:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16).
[ 12.881906] sd 1:0:0:0: [sdb] Attached SCSI disk
[ 13.946160] gpiomem-bcm2835 3f200000.gpiomem: Initialised: Registers at 0x3f200000
[ 13.957666] bcm2835-rng 3f104000.rng: hwrng registered
[ 14.022165] snd-rpi-iqaudio-dac soc:sound: ASoC: CODEC DAI pcm512x-hifi not registered - will retry
[ 14.181087] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[ 14.190832] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
--
[ 20.184910] wlan0: RX AssocResp from 00:25:9c:13:e7:12 (capab=0x431 status=0 aid=4)
[ 20.301723] wlan0: associated
[ 20.306827] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[ 110.045728] pcm512x 1-004c: No SCLK, using BCLK: -2
[ 111.975428] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[ 1428.731832] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null)
[ 9204.593083] pcm512x 1-004c: No SCLK, using BCLK: -2
[17467.143120] pcm512x 1-004c: No SCLK, using BCLK: -2
[17499.068650] pcm512x 1-004c: No SCLK, using BCLK: -2
')

I try to mount it (as root) and it purports to mount...

$this->bbcode_second_pass_code('', '
# mount -v -t auto /dev/sdb1 /mnt/seagate-5tb
mount: /dev/sdb1 mounted on /mnt/seagate-5tb.
# dmesg | tail -n3
[17467.143120] pcm512x 1-004c: No SCLK, using BCLK: -2
[17499.068650] pcm512x 1-004c: No SCLK, using BCLK: -2
[180078.489600] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null)
')

However the drive is not detected by df nor can I ls the device...
$this->bbcode_second_pass_code('', '
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/root 15G 8.1G 5.5G 60% /
devtmpfs 464M 0 464M 0% /dev
tmpfs 469M 0 469M 0% /dev/shm
tmpfs 469M 468K 468M 1% /run
tmpfs 469M 0 469M 0% /sys/fs/cgroup
tmpfs 469M 4.0K 468M 1% /tmp
/dev/mmcblk0p1 100M 24M 77M 24% /boot
/dev/sda1 917G 867G 3.5G 100% /mnt/backup-music
tmpfs 94M 0 94M 0% /run/user/1001
# ls /mnt/seagate-5tb/
ls: cannot access '/mnt/seagate-5tb/': No such device
')

The kernel seems to have detected the device ok and ext4 is supported I think as its listed in /proc/filesystems

$this->bbcode_second_pass_code('', '
# cat /proc/filesystems
nodev sysfs
nodev rootfs
nodev ramfs
nodev bdev
nodev proc
nodev cpuset
nodev cgroup
nodev cgroup2
nodev tmpfs
nodev devtmpfs
nodev configfs
nodev debugfs
nodev tracefs
nodev securityfs
nodev sockfs
nodev bpf
nodev pipefs
nodev rpc_pipefs
nodev devpts
reiserfs
ext3
ext2
ext4
vfat
msdos
nodev nfs
nodev nfs4
nodev autofs
nodev overlay
jfs
xfs
f2fs
nodev mqueue
btrfs
')

...so I'm somewhat stumped as to why the device isn't mounting correctly and would be grateful for any suggestions/pointers to investigate or try.

Thanks in advance,

slackline