can I use two 4 TB disk powered by USB on RPI-4? No external power supply

Question

I use 1 usb powered 4 TB disk sda without issues on RPI-4. Now I added a second usb powered 4 TB disk sdb and receive lots of errors (from both devices):

# lsblk 
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda           8:0    0  3.7T  0 disk 
`-sda1        8:1    0  3.7T  0 part /data
sdb           8:16   0  3.7T  0 disk 
mmcblk0     179:0    0 29.7G  0 disk 
|-mmcblk0p1 179:1    0  256M  0 part /boot
`-mmcblk0p2 179:2    0 29.5G  0 part /

Logs:

[Sun Jan  5 11:40:06 2020] print_req_error: I/O error, dev sdb, sector 4
[Sun Jan  5 11:40:06 2020] Buffer I/O error on dev sdb, logical block 4, async page read
[Sun Jan  5 11:40:06 2020] sd 1:0:0:0: [sdb] tag#10 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x06
[Sun Jan  5 11:40:06 2020] sd 1:0:0:0: [sdb] tag#10 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 02 00 00 00 01 00 00
[Sun Jan  5 11:40:06 2020] print_req_error: I/O error, dev sdb, sector 2
[Sun Jan  5 11:40:06 2020] Buffer I/O error on dev sdb, logical block 2, async page read
[Sun Jan  5 11:40:06 2020] sd 1:0:0:0: [sdb] tag#9 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x06
[Sun Jan  5 11:40:06 2020] sd 1:0:0:0: [sdb] tag#9 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 01 00 00 00 01 00 00
[Sun Jan  5 11:40:06 2020] print_req_error: I/O error, dev sdb, sector 1
[Sun Jan  5 11:40:06 2020] Buffer I/O error on dev sdb, logical block 1, async page read
[Sun Jan  5 11:40:06 2020] sd 1:0:0:0: [sdb] tag#4 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x06
[Sun Jan  5 11:40:06 2020] sd 1:0:0:0: [sdb] tag#4 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00
[Sun Jan  5 11:40:06 2020] print_req_error: I/O error, dev sdb, sector 0
[Sun Jan  5 11:40:06 2020] Buffer I/O error on dev sdb, logical block 0, async page read
[Sun Jan  5 11:40:09 2020] scsi host0: uas_eh_device_reset_handler start
[Sun Jan  5 11:40:09 2020] sd 0:0:0:0: [sda] tag#19 uas_zap_pending 0 uas-tag 2 inflight: CMD 
[Sun Jan  5 11:40:09 2020] sd 0:0:0:0: [sda] tag#19 CDB: opcode=0x88 88 00 00 00 00 00 49 1f cd 20 00 00 01 60 00 00
[Sun Jan  5 11:40:09 2020] sd 0:0:0:0: [sda] tag#20 uas_zap_pending 0 uas-tag 3 inflight: CMD 
[Sun Jan  5 11:40:09 2020] sd 0:0:0:0: [sda] tag#20 CDB: opcode=0x8a 8a 00 00 00 00 00 e8 d3 6f 60 00 00 00 10 00 00
[Sun Jan  5 11:40:09 2020] usb 2-1: reset SuperSpeed Gen 1 USB device number 2 using xhci_hcd
[Sun Jan  5 11:40:09 2020] scsi host0: uas_eh_device_reset_handler success

and

[Sun Jan  5 11:39:01 2020] Workqueue: events_unbound async_run_entry_fn
[Sun Jan  5 11:39:01 2020] [<c0997424>] (__schedule) from [<c0997a94>] (schedule+0x50/0xa8)
[Sun Jan  5 11:39:01 2020] [<c0997a94>] (schedule) from [<c0997fcc>] (io_schedule+0x20/0x40)
[Sun Jan  5 11:39:01 2020] [<c0997fcc>] (io_schedule) from [<c0337d10>] (wait_on_page_bit+0x124/0x15c)
[Sun Jan  5 11:39:01 2020] [<c0337d10>] (wait_on_page_bit) from [<c0338da0>] (do_read_cache_page+0x1c4/0x37c)
[Sun Jan  5 11:39:01 2020] [<c0338da0>] (do_read_cache_page) from [<c0338f7c>] (read_cache_page+0x24/0x2c)
[Sun Jan  5 11:39:01 2020] [<c0338f7c>] (read_cache_page) from [<c05dd51c>] (read_dev_sector+0x38/0xb8)
[Sun Jan  5 11:39:01 2020] [<c05dd51c>] (read_dev_sector) from [<c05e0704>] (msdos_partition+0xb4/0x704)
[Sun Jan  5 11:39:01 2020] [<c05e0704>] (msdos_partition) from [<c05dfd08>] (check_partition+0x118/0x1f4)
[Sun Jan  5 11:39:01 2020] [<c05dfd08>] (check_partition) from [<c05ddc94>] (rescan_partitions+0x94/0x478)
[Sun Jan  5 11:39:01 2020] [<c05ddc94>] (rescan_partitions) from [<c03f31d0>] (__blkdev_get+0x2fc/0x4c4)
[Sun Jan  5 11:39:01 2020] [<c03f31d0>] (__blkdev_get) from [<c03f3508>] (blkdev_get+0x170/0x3c4)
[Sun Jan  5 11:39:01 2020] [<c03f3508>] (blkdev_get) from [<c05dc114>] (__device_add_disk+0x484/0x4ec)
[Sun Jan  5 11:39:01 2020] [<c05dc114>] (__device_add_disk) from [<c05dc198>] (device_add_disk+0x1c/0x20)
[Sun Jan  5 11:39:01 2020] [<c05dc198>] (device_add_disk) from [<c072a538>] (sd_probe_async+0xf0/0x184)
[Sun Jan  5 11:39:01 2020] [<c072a538>] (sd_probe_async) from [<c0247c24>] (async_run_entry_fn+0x54/0x118)
[Sun Jan  5 11:39:01 2020] [<c0247c24>] (async_run_entry_fn) from [<c023db40>] (process_one_work+0x170/0x458)
[Sun Jan  5 11:39:01 2020] [<c023db40>] (process_one_work) from [<c023de84>] (worker_thread+0x5c/0x5a4)
[Sun Jan  5 11:39:01 2020] [<c023de84>] (worker_thread) from [<c0244170>] (kthread+0x138/0x168)
[Sun Jan  5 11:39:01 2020] [<c0244170>] (kthread) from [<c02010ac>] (ret_from_fork+0x14/0x28)
[Sun Jan  5 11:39:01 2020] Exception stack(0xc2661fb0 to 0xc2661ff8)
[Sun Jan  5 11:39:01 2020] 1fa0:                                     00000000 00000000 00000000 00000000
[Sun Jan  5 11:39:01 2020] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[Sun Jan  5 11:39:01 2020] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[Sun Jan  5 11:39:01 2020] INFO: task mount:24772 blocked for more than 120 seconds.
[Sun Jan  5 11:39:01 2020]       Tainted: G         C        4.19.75-v7l+ #1270
[Sun Jan  5 11:39:01 2020] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Sun Jan  5 11:39:01 2020] mount           D    0 24772  24767 0x00000000
[Sun Jan  5 11:39:01 2020] [<c0997424>] (__schedule) from [<c0997a94>] (schedule+0x50/0xa8)
[Sun Jan  5 11:39:01 2020] [<c0997a94>] (schedule) from [<c0997ef0>] (schedule_preempt_disabled+0x18/0x1c)
[Sun Jan  5 11:39:01 2020] [<c0997ef0>] (schedule_preempt_disabled) from [<c0998fa0>] (__mutex_lock.constprop.5+0x1a8/0x590)
[Sun Jan  5 11:39:01 2020] [<c0998fa0>] (__mutex_lock.constprop.5) from [<c09994a4>] (__mutex_lock_slowpath+0x1c/0x20)
[Sun Jan  5 11:39:01 2020] [<c09994a4>] (__mutex_lock_slowpath) from [<c0999504>] (mutex_lock+0x5c/0x60)
[Sun Jan  5 11:39:01 2020] [<c0999504>] (mutex_lock) from [<c03f3010>] (__blkdev_get+0x13c/0x4c4)
[Sun Jan  5 11:39:01 2020] [<c03f3010>] (__blkdev_get) from [<c03f3508>] (blkdev_get+0x170/0x3c4)
[Sun Jan  5 11:39:01 2020] [<c03f3508>] (blkdev_get) from [<c03f3c18>] (blkdev_open+0x90/0x9c)
[Sun Jan  5 11:39:01 2020] [<c03f3c18>] (blkdev_open) from [<c03aba0c>] (do_dentry_open+0x23c/0x3c0)
[Sun Jan  5 11:39:01 2020] [<c03aba0c>] (do_dentry_open) from [<c03acee8>] (vfs_open+0x3c/0x40)
[Sun Jan  5 11:39:01 2020] [<c03acee8>] (vfs_open) from [<c03bf820>] (path_openat+0x428/0x1024)
[Sun Jan  5 11:39:01 2020] [<c03bf820>] (path_openat) from [<c03c1708>] (do_filp_open+0x80/0xec)
[Sun Jan  5 11:39:01 2020] [<c03c1708>] (do_filp_open) from [<c03ad1c8>] (do_sys_open+0x140/0x1f0)
[Sun Jan  5 11:39:01 2020] [<c03ad1c8>] (do_sys_open) from [<c03ad2c4>] (sys_openat+0x1c/0x20)
[Sun Jan  5 11:39:01 2020] [<c03ad2c4>] (sys_openat) from [<c0201000>] (ret_fast_syscall+0x0/0x28)
[Sun Jan  5 11:39:01 2020] Exception stack(0xc2fb7fa8 to 0xc2fb7ff0)
[Sun Jan  5 11:39:01 2020] 7fa0:                   00995bb8 00028cc0 ffffff9c 00995bb8 000a0000 00000000
[Sun Jan  5 11:39:01 2020] 7fc0: 00995bb8 00028cc0 bec633c4 00000142 00000002 00995df8 b6f520e8 00000002
[Sun Jan  5 11:39:01 2020] 7fe0: b6ebc000 bec63348 b6d28358 b6e37464

and

[Sun Jan  5 11:28:46 2020] usb 2-2: new SuperSpeed Gen 1 USB device number 3 using xhci_hcd
[Sun Jan  5 11:28:46 2020] usb 2-2: New USB device found, idVendor=0bc2, idProduct=ab28, bcdDevice= 1.00
[Sun Jan  5 11:28:46 2020] usb 2-2: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[Sun Jan  5 11:28:46 2020] usb 2-2: Product: BUP RD
[Sun Jan  5 11:28:46 2020] usb 2-2: Manufacturer: Seagate
[Sun Jan  5 11:28:46 2020] usb 2-2: SerialNumber: NA9FHMK4
[Sun Jan  5 11:28:46 2020] scsi host1: uas
[Sun Jan  5 11:28:46 2020] scsi 1:0:0:0: Direct-Access     Seagate  BUP RD           0304 PQ: 0 ANSI: 6
[Sun Jan  5 11:28:46 2020] sd 1:0:0:0: [sdb] Spinning up disk...
[Sun Jan  5 11:28:46 2020] sd 1:0:0:0: Attached scsi generic sg1 type 0
[Sun Jan  5 11:28:47 2020] ................................................................................................not responding...
[Sun Jan  5 11:30:27 2020] sd 1:0:0:0: [sdb] 7814037167 512-byte logical blocks: (4.00 TB/3.64 TiB)
[Sun Jan  5 11:30:27 2020] sd 1:0:0:0: [sdb] 2048-byte physical blocks
[Sun Jan  5 11:30:48 2020] sd 1:0:0:0: [sdb] Test WP failed, assume Write Enabled
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#27 uas_eh_abort_handler 0 uas-tag 2 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#27 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 01 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#26 uas_eh_abort_handler 0 uas-tag 1 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#26 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#5 uas_eh_abort_handler 0 uas-tag 8 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#5 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 07 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#4 uas_eh_abort_handler 0 uas-tag 7 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#4 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 06 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#3 uas_eh_abort_handler 0 uas-tag 6 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#3 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 05 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#2 uas_eh_abort_handler 0 uas-tag 5 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#2 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 04 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#1 uas_eh_abort_handler 0 uas-tag 4 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#1 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 03 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#0 uas_eh_abort_handler 0 uas-tag 3 inflight: CMD IN 
[Sun Jan  5 11:30:51 2020] sd 0:0:0:0: [sda] tag#0 CDB: opcode=0x88 88 00 00 00 00 00 00 00 00 02 00 00 00 01 00 00
[Sun Jan  5 11:30:51 2020] scsi host0: uas_eh_device_reset_handler start
[Sun Jan  5 11:30:51 2020] usb 2-1: reset SuperSpeed Gen 1 USB device number 2 using xhci_hcd
[Sun Jan  5 11:30:51 2020] scsi host0: uas_eh_device_reset_handler success
[Sun Jan  5 11:30:54 2020] sd 1:0:0:0: [sdb] Asking for cache data failed
[Sun Jan  5 11:30:54 2020] sd 1:0:0:0: [sdb] Assuming drive cache: write through
[Sun Jan  5 11:30:54 2020] sd 1:0:0:0: [sdb] Optimal transfer size 33553920 bytes not a multiple of physical block size (2048 bytes)
[Sun Jan  5 11:30:54 2020] sd 1:0:0:0: [sdb] Spinning up disk...

My guess is that RPI-4 can't handle 2 usb powered disks. Both disks are fine, but the logs say there are problems.

You have the correct answer to your question, but if you want to overcome this issue, you can add a powered USB hub to your system to overcome the problem. This will allow you to use both drives on your RPi. — Seamus, Jan 06 '20 at 04:14
I can't answer that question from my own personal experience, but it does say it's been "Verified". If I were in your shoes, I'd probably go for it as long as the reseller/retailer allowed a return within a reasonable amount of time. Also, after you've got this working, you can help others here by following up & posting what solution worked for you. — Seamus, Jan 06 '20 at 08:00

Michael Harvey · Accepted Answer · 2023-07-02T10:11:55.283

6

"My guess is that RPI-4 can't handle 2 usb powered disks. Both disks are fine, but the logs say there are problems."

Your guess is correct. This is something that appears regularly on Raspberry Pi forums. The Rpi 4, like the other models, can supply 1.2 A total to all USB ports. That is, the maximum is shared. Most 'portable' type USB powered drives take around 1 amp maximum current; less when idle, up to the maximum when starting to spin, or when doing seeks. Two drives will easily break the 1.2 A limit. This means unreliable and flaky operation for all drives when two or more are taking their power from the Pi's USB ports, sometimes even preventing boot.

I have actually experienced this myself. I had loud clicking/chirping noises from a Toshiba Canvio 1TB and a WD Elements 2TB drive when both were plugged into an Rpi 4 at the same time. Also file system corruption. However, with the WD 2TB USB powered drive, and a Seagate Backup Plus 3TB drive with its own AC power adapter, everything works fine. Each is connected to one of the Pi's USB-3 ports and they form the storage for a NAS and are formatted ext4 as using NTFS brings speed problems on Linux systems.

Note: as advised by the Raspberry Pi Foundation, I use an Official Raspberry Pi 4 Power Supply. Not using one has been shown to be the cause of intermittent problems or issues of many kinds.

edited Jul 02 '23 at 10:11

answered Jan 05 '20 at 20:59

Michael Harvey

1,390
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Could you share which AC power adapter are you using ? – Michael Aguilar Jul 01 '23 at 22:21
@MichaelAguilar - please see new additional part of my answer. – Michael Harvey Jul 02 '23 at 08:17
So you are able to use 2 external disks (probable exceeding the 1.2 amp limit by USB) only using the official power supply? – Michael Aguilar Jul 03 '23 at 13:51
@MichaelAguilar - in my answer: (1) WD 2TB USB powered drive, and (2) a Seagate Backup Plus 3TB drive with its own AC power adapter, everything works fine. For disk (1) the USB on the Pi supplies power and data connection, and for disk (2) the USB on the Pi is only used for data, since that disk has it own PSU wall plug, a black one. – Michael Harvey Jul 03 '23 at 14:45
Oh got it. Thanks for the clarification – Michael Aguilar Jul 03 '23 at 16:00

can I use two 4 TB disk powered by USB on RPI-4? No external power supply

1 Answers1