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Recently I bought a new Maxtor M3 Portable external HDD with USB 3.0. During file transfers it had very slow writing speed, starting at 75 MB/s and decaying fastly to <1 MB/s.

What I tried:

  • using another USB cable
  • updating BIOS of my ASUS F555LB notebook
  • reformatting to NTFS with gparted and windows partition manager

Benchmarks:

  • with Opensuse 15 (gnome-disks):

Average read rate: 33.9 MB/s Average write rate: 7.8 MB/s Average access time: 126.79 ms

  • with Windows 10 (winsat disk -drive f):

Disk Random 16.0 Read: 0.71 MB/s Disk Sequential 64.0 Read: 84.89 MB/s Disk Sequential 64.0 Write: 100.98 MB/s Average sequential reading time: 16.426 ms Latency: 95. Perzentil: 175.989 ms Latency: Maximum: 337.168 ms Average random reading time: 32.446 ms

  • with my old Samsung external HDD (USB 2.0) at the same USB port (gnome-disks)

Average read rate: 43.6 MB/s Average write rate: 45.3 MB/s Average access time: 17.37 ms

Other outputs:

  • lsusb

Bus 002 Device 004: ID 0bc2:61b5 Seagate RSS LLC Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 004: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller Bus 001 Device 003: ID 0bda:57b5 Realtek Semiconductor Corp. Bus 001 Device 002: ID 046a:000c Cherry GmbH Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

  • dmesg after connecting the HDD and disconnecting a few seconds later:

[ 5020.734131] usb 2-2: new SuperSpeed USB device number 6 using xhci_hcd [ 5020.755083] usb 2-2: New USB device found, idVendor=0bc2, idProduct=61b5 [ 5020.755085] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 5020.755086] usb 2-2: Product: M3 Portable [ 5020.755087] usb 2-2: Manufacturer: Seagate [ 5020.755088] usb 2-2: SerialNumber: NM14NP6K [ 5020.757023] scsi host4: uas [ 5020.757443] scsi 4:0:0:0: Direct-Access Seagate M3 Portable 0708 PQ: 0 ANSI: 6 [ 5020.758104] sd 4:0:0:0: Attached scsi generic sg2 type 0 [ 5025.320334] sd 4:0:0:0: [sdb] 3907029167 512-byte logical blocks: (2.00 TB/1.82 TiB) [ 5025.320336] sd 4:0:0:0: [sdb] 4096-byte physical blocks [ 5025.320477] sd 4:0:0:0: [sdb] Write Protect is off [ 5025.320478] sd 4:0:0:0: [sdb] Mode Sense: 53 00 00 08 [ 5025.320751] sd 4:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 5025.353086] sdb: sdb1 [ 5025.354544] sd 4:0:0:0: [sdb] Attached SCSI disk [ 5048.241828] xhci_hcd 0000:00:14.0: Cannot set link state. [ 5048.241832] usb usb2-port2: cannot disable (err = -32) [ 5048.241835] usb 2-2: USB disconnect, device number 6 [ 5048.257992] sd 4:0:0:0: [sdb] Synchronizing SCSI cache [ 5048.509816] sd 4:0:0:0: [sdb] Synchronize Cache(10) failed: Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK

  • fdisk -l

Festplatte /dev/sdb: 1,8 TiB, 2000398933504 Bytes, 3907029167 Sektoren Einheiten: Sektoren von 1 * 512 = 512 Bytes Sektorgröße (logisch/physikalisch): 512 Bytes / 4096 Bytes E/A-Größe (minimal/optimal): 4096 Bytes / 33553920 Bytes Festplattenbezeichnungstyp: dos Festplattenbezeichner: 0x32411175

Gerät Boot Anfang Ende Sektoren Größe Kn Typ /dev/sdb1 2048 3907028991 3907026944 1,8T 7 HPFS/NTFS/exFAT

I guess the slow speed could be caused by the SCSI cache error, but I didn't find anything how to proceed. Is there a way to fix it?

Update

After disabling UAS, dmesg shows

[ 152.262070] usb 2-2: UAS is blacklisted for this device, using usb-storage instead [ 152.262072] usb-storage 2-2:1.0: USB Mass Storage device detected [ 152.262143] usb-storage 2-2:1.0: Quirks match for vid 0bc2 pid 61b5: 800000 [ 152.262165] scsi host4: usb-storage 2-2:1.0

instead of scsi host4: uas. Unfortunately the benchmark is even worse:

Average read rate: 10.0 MB/s Average write rate: 1.0 MB/s Average access time: 133.61 ms

closed as off-topic by user88036, terdon Sep 24 '18 at 17:39

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions describing a problem that can't be reproduced and seemingly went away on its own (or went away when a typo was fixed) are off-topic as they are unlikely to help future readers." – Community, terdon
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    Your drive seems to be using the UAS usb attached scsi protocol. Some enclosures have buggy implementations (that probably have manufacturer workarounds in proprietary OSes). Check out this answer on disabling UASP. – meuh Aug 12 '18 at 15:18
  • I disabled UASP and updated the question accordingly. Unfortunately it's even slower. – Marph Aug 12 '18 at 18:55
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It turned out to be a hardware defect. I got a new drive and everything works as excpected.

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