TerraMaster Forum

i have a d6320 connected to a f6-424max the purpose of this is to backup the 424. i want to establish a storage pool on it and setup backup jobs

however, i keep getting a error that the drives are getting disconnected, and the sync fails and the pool disappears. i have also created a volume on the pool during the sync process and that volume is also missing (no data was on it). so both the pool and the volume do not present, a on off of the d6 does not yield the poll to show up again (pool 3)





however in disks the two drives i have mouted in the d6 still show connected.

Try a different cable to connect them.

Please operate according to the following instructions:
1.Check if the USB connection is secure; try unplugging and replugging it.
2.Try connecting the hard drive to a different slot.
3.Restart the device.

TMeric wrote: ↑27 Nov 2024, 21:37 Please operate according to the following instructions:
1.Check if the USB connection is secure; try unplugging and replugging it.
2.Try connecting the hard drive to a different slot.
3.Restart the device.

i re seated the data cable (TM provided inbox cable), re attempted still failed, power cycles both by button as well as A/C disconnected the DAS, re attempted and failed.

i rebooted the 424max and on the forth attempt the storage pool synced. but yeh gives me pause on putting any data on it if its just going to dissolve randomly

Check your syslog for USB error messages. I've experienced issues with USB connect ups.

i added 4 more drives to the d6-320 and the storage pool dissolved again, all 6 disks show as online. however, tos is not seeing the pool now (storagepool3) i did nothing with the two disks that made up storage pool3, i only added 4 more to the unit not even too the pool as the pool then errored degraded

i rebooted teh 424max and now the storagepool3 shows backup. this really feels like a bug that plug and play is not working and when the d6 gets anything of variability into it it just can reconnect the drives that the pool needs to be brought up in a boot cycle. this is less then ideal gives me concerns about allow drives to sleep as well to save power because if they wake that could dissolve the pool.

TMeric wrote: ↑27 Nov 2024, 21:37

and less then 5 min into trying to add the 4 new disks to storage pool 3 (i couldnt edit was greyed out so i had to delete 3 and re create useing all 6 disks) it started the sync and seconds later it spammed me that all the drives are disconnected. yet they all show as connected

this is wild unstable

TMeric wrote: ↑27 Nov 2024, 21:37

i have now also tried different USB 3.1 cables

here is the log via the command 'dmesg'


[ 1396.734000] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.741002] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.741008] usb 2-3.3-port4: Cannot enable. Maybe the USB cable is bad?
[ 1396.748000] usb 2-3.3-port4: cannot disable (err = -71)
[ 1396.755001] hub 2-3.3:1.0: hub_ext_port_status failed (err = -71)
[ 1396.761973] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.763753] sd 45:0:0:0: [sds] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x07 driverbyte=DRIVER_OK cmd_age=0s
[ 1396.763758] sd 45:0:0:0: [sds] tag#0 CDB: opcode=0x88 88 00 00 00 00 00 01 5a 1a 68 00 00 08 00 00 00
[ 1396.763759] I/O error, dev sds, sector 22682216 op 0x0:(READ) flags 0x4000 phys_seg 256 prio class 2
[ 1396.768975] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.775769] sd 46:0:0:0: [sdt] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x07 driverbyte=DRIVER_OK cmd_age=0s
[ 1396.775776] sd 46:0:0:0: [sdt] tag#0 CDB: opcode=0x88 88 00 00 00 00 00 01 5a 24 68 00 00 08 00 00 00
[ 1396.775777] I/O error, dev sdt, sector 22684776 op 0x0:(READ) flags 0x4000 phys_seg 256 prio class 2
[ 1396.775978] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.782983] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.789975] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.789988] usb 2-3.3-port4: Cannot enable. Maybe the USB cable is bad?
[ 1396.796978] usb 2-3.3-port4: cannot disable (err = -71)
[ 1396.803992] hub 2-3.3:1.0: hub_ext_port_status failed (err = -71)
[ 1396.805781] sd 45:0:0:0: [sds] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x07 driverbyte=DRIVER_OK cmd_age=0s
[ 1396.805787] sd 45:0:0:0: [sds] tag#0 CDB: opcode=0x88 88 00 00 00 00 00 01 5a 22 68 00 00 08 00 00 00
[ 1396.805788] I/O error, dev sds, sector 22684264 op 0x0:(READ) flags 0x4000 phys_seg 256 prio class 2
[ 1396.811048] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.817979] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.821767] sd 46:0:0:0: [sdt] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x07 driverbyte=DRIVER_OK cmd_age=0s
[ 1396.821774] sd 46:0:0:0: [sdt] tag#0 CDB: opcode=0x88 88 00 00 00 00 00 01 5a 2c 68 00 00 00 40 00 00
[ 1396.821776] I/O error, dev sdt, sector 22686824 op 0x0:(READ) flags 0x0 phys_seg 8 prio class 2
[ 1396.824985] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.832007] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.838978] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.838989] usb 2-3.3-port4: Cannot enable. Maybe the USB cable is bad?
[ 1396.845970] usb 2-3.3-port4: cannot disable (err = -71)
[ 1396.846749] sd 45:0:0:0: [sds] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x07 driverbyte=DRIVER_OK cmd_age=0s
[ 1396.846754] sd 45:0:0:0: [sds] tag#0 CDB: opcode=0x88 88 00 00 00 00 00 01 5a 2a 68 00 00 02 40 00 00
[ 1396.846755] I/O error, dev sds, sector 22686312 op 0x0:(READ) flags 0x0 phys_seg 72 prio class 2
[ 1396.852981] hub 2-3.3:1.0: hub_ext_port_status failed (err = -71)
[ 1396.860013] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.867029] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.874039] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.881004] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.886771] sd 45:0:0:0: [sds] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x07 driverbyte=DRIVER_OK cmd_age=0s
[ 1396.886776] sd 45:0:0:0: [sds] tag#0 CDB: opcode=0x88 88 00 00 00 00 00 01 5a 0a 68 00 00 00 08 00 00
[ 1396.886778] I/O error, dev sds, sector 22678120 op 0x0:(READ) flags 0x4000 phys_seg 1 prio class 2
[ 1396.888037] usb 2-3.3-port4: cannot reset (err = -71)
[ 1396.888043] usb 2-3.3-port4: Cannot enable. Maybe the USB cable is bad?
[ 1396.895037] usb 2-3.3-port4: cannot disable (err = -71)
[ 1396.902011] usb 2-3.3-port4: cannot disable (err = -71)
[ 1396.909011] hub 2-3.3:1.0: hub_ext_port_status failed (err = -71)
[ 1396.916006] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.923043] hub 2-3.3:1.0: hub_ext_port_status failed (err = -71)
[ 1396.929975] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.937018] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.943978] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.951010] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.951020] usb 2-3.3-port3: Cannot enable. Maybe the USB cable is bad?
[ 1396.958010] usb 2-3.3-port3: cannot disable (err = -71)
[ 1396.965009] hub 2-3.3:1.0: hub_ext_port_status failed (err = -71)
[ 1396.971980] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.978974] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.982720] usb 2-3: USB disconnect, device number 26
[ 1396.982728] usb 2-3.1: USB disconnect, device number 27
[ 1396.982907] [292]: scst: scst_unregister_deviceDetached from scsi45, channel 0, id 0, lun 0, type 0
[ 1396.985976] usb 2-3.3-port3: cannot reset (err = -71)
[ 1396.986014] usb 2-3.3.1: USB disconnect, device number 30
[ 1396.986728] md/raid:md5: 1100 read_errors > 1099 stripes
[ 1396.986733] md/raid:md5: Too many read errors, failing device sds4.
[ 1396.986735] md/raid:md5: Disk failure on sds4, disabling device.
[ 1396.986742] md/raid:md5: Operation continuing on 5 devices.
[ 1396.986757] raid5_end_read_request: 111 callbacks suppressed
[ 1396.986759] md/raid:md5: read error not correctable (sector 2091656 on sds4).
[ 1396.986762] md/raid:md5: read error not correctable (sector 2091664 on sds4).
[ 1396.986764] md/raid:md5: read error not correctable (sector 2091672 on sds4).
[ 1396.986765] md/raid:md5: read error not correctable (sector 2091680 on sds4).
[ 1396.986768] md/raid:md5: read error not correctable (sector 2091688 on sds4).
[ 1396.986770] md/raid:md5: read error not correctable (sector 2091696 on sds4).
[ 1396.986771] md/raid:md5: read error not correctable (sector 2091704 on sds4).
[ 1396.986773] md/raid:md5: read error not correctable (sector 2091712 on sds4).
[ 1396.986775] md/raid:md5: read error not correctable (sector 2091720 on sds4).
[ 1396.986777] md/raid:md5: read error not correctable (sector 2091728 on sds4).
[ 1396.990746] md: super_written gets error=-19
[ 1396.990760] md/raid:md5: Disk failure on sdu4, disabling device.
[ 1396.990765] md/raid:md5: Cannot continue operation (2/6 failed).
[ 1396.991984] [66915]: scst: scst_unregister_deviceDetached from scsi47, channel 0, id 0, lun 0, type 0
[ 1397.012780] sd 45:0:0:0: [sds] Synchronizing SCSI cache
[ 1397.013041] sd 45:0:0:0: [sds] Synchronize Cache(10) failed: Result: hostbyte=0x01 driverbyte=DRIVER_OK
[ 1397.014280] usb 2-3.3: USB disconnect, device number 28
[ 1397.023793] sd 47:0:0:0: [sdu] Synchronizing SCSI cache
[ 1397.023869] sd 47:0:0:0: [sdu] Synchronize Cache(10) failed: Result: hostbyte=0x01 driverbyte=DRIVER_OK
[ 1397.024848] usb 2-3.3.2: USB disconnect, device number 31
[ 1397.025264] [66915]: scst: scst_unregister_deviceDetached from scsi48, channel 0, id 0, lun 0, type 0
[ 1397.028760] md: super_written gets error=-5
[ 1397.028775] md/raid:md5: Disk failure on sdt4, disabling device.
[ 1397.028781] md/raid:md5: Cannot continue operation (3/6 failed).
[ 1397.031895] md: super_written gets error=-19
[ 1397.031913] md/raid:md5: Disk failure on sdv4, disabling device.
[ 1397.031918] md/raid:md5: Cannot continue operation (4/6 failed).
[ 1397.054808] sd 48:0:0:0: [sdv] Synchronizing SCSI cache
[ 1397.054870] sd 48:0:0:0: [sdv] Synchronize Cache(10) failed: Result: hostbyte=0x01 driverbyte=DRIVER_OK
[ 1397.056122] usb 2-3.3.3: USB disconnect, device number 32
[ 1397.057282] [66915]: scst: scst_unregister_deviceDetached from scsi49, channel 0, id 0, lun 0, type 0
[ 1397.060944] md: super_written gets error=-5
[ 1397.060960] md/raid:md5: Disk failure on sdx4, disabling device.
[ 1397.060966] md/raid:md5: Cannot continue operation (5/6 failed).
[ 1397.065842] md: super_written gets error=-19
[ 1397.065859] md/raid:md5: Disk failure on sdw4, disabling device.
[ 1397.065865] md/raid:md5: Cannot continue operation (6/6 failed).
[ 1397.068731] md: md5: resync interrupted.
[ 1397.088801] sd 49:0:0:0: [sdw] Synchronizing SCSI cache
[ 1397.088857] sd 49:0:0:0: [sdw] Synchronize Cache(10) failed: Result: hostbyte=0x01 driverbyte=DRIVER_OK
[ 1397.090420] usb 2-3.3.4: USB disconnect, device number 33
[ 1397.094288] [66915]: scst: scst_unregister_deviceDetached from scsi50, channel 0, id 0, lun 0, type 0
[ 1397.107977] md: resync of RAID array md5
[ 1397.108003] md: md5: resync done.
[ 1397.133815] sd 50:0:0:0: [sdx] Synchronizing SCSI cache
[ 1397.134024] sd 50:0:0:0: [sdx] Synchronize Cache(10) failed: Result: hostbyte=0x01 driverbyte=DRIVER_OK
[ 1397.136206] usb 2-3.4: USB disconnect, device number 29
[ 1397.136376] [292]: scst: scst_unregister_deviceDetached from scsi46, channel 0, id 0, lun 0, type 0
[ 1397.167804] sd 46:0:0:0: [sdt] Synchronizing SCSI cache
[ 1397.168011] sd 46:0:0:0: [sdt] Synchronize Cache(10) failed: Result: hostbyte=0x01 driverbyte=DRIVER_OK
[ 1397.395588] usb 2-3: new SuperSpeed Plus Gen 2x1 USB device number 34 using xhci_hcd
[ 1397.424367] usb 2-3: New USB device found, idVendor=0bda, idProduct=0420, bcdDevice= 0.01
[ 1397.424377] usb 2-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1397.424379] usb 2-3: Product: 4-Port USB 3.0 Hub
[ 1397.424381] usb 2-3: Manufacturer: TerraMaster
[ 1397.432653] hub 2-3:1.0: USB hub found
[ 1397.434087] hub 2-3:1.0: 4 ports detected
[ 1397.989098] buffer_io_error: 16 callbacks suppressed
[ 1397.989104] Buffer I/O error on dev md5, logical block 4, async page read
[ 1397.990974] Buffer I/O error on dev md5, logical block 0, lost async page write
[ 1397.991057] Buffer I/O error on dev md5, logical block 4, async page read
[ 1398.120785] usb 2-3.1: new SuperSpeed Plus Gen 2x1 USB device number 35 using xhci_hcd
[ 1398.134263] usb 2-3.1: New USB device found, idVendor=235c, idProduct=a006, bcdDevice= 1.00
[ 1398.134268] usb 2-3.1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 1398.134270] usb 2-3.1: Product: TDAS
[ 1398.134271] usb 2-3.1: Manufacturer: TerraMaster
[ 1398.134273] usb 2-3.1: SerialNumber: 202404120029
[ 1398.136347] usb-storage 2-3.1:1.0: USB Mass Storage device detected
[ 1398.136486] scsi host51: usb-storage 2-3.1:1.0
[ 1398.209577] usb 2-3.3: new SuperSpeed Plus Gen 2x1 USB device number 36 using xhci_hcd
[ 1398.238819] usb 2-3.3: New USB device found, idVendor=0bda, idProduct=0420, bcdDevice= 0.01
[ 1398.238825] usb 2-3.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1398.238827] usb 2-3.3: Product: 4-Port USB 3.0 Hub
[ 1398.238828] usb 2-3.3: Manufacturer: TerraMaster
[ 1398.247480] hub 2-3.3:1.0: USB hub found
[ 1398.248959] hub 2-3.3:1.0: 4 ports detected
[ 1398.321805] usb 2-3.4: new SuperSpeed Plus Gen 2x1 USB device number 37 using xhci_hcd
[ 1398.334322] usb 2-3.4: New USB device found, idVendor=235c, idProduct=a006, bcdDevice= 1.00
[ 1398.334329] usb 2-3.4: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 1398.334330] usb 2-3.4: Product: TDAS
[ 1398.334332] usb 2-3.4: Manufacturer: TerraMaster
[ 1398.334333] usb 2-3.4: SerialNumber: 202404120029
[ 1398.336734] usb-storage 2-3.4:1.0: USB Mass Storage device detected
[ 1398.336881] scsi host52: usb-storage 2-3.4:1.0
[ 1398.926855] usb 2-3.3.1: new SuperSpeed Plus Gen 2x1 USB device number 38 using xhci_hcd
[ 1398.939377] usb 2-3.3.1: New USB device found, idVendor=235c, idProduct=a006, bcdDevice= 1.00
[ 1398.939382] usb 2-3.3.1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 1398.939383] usb 2-3.3.1: Product: TDAS
[ 1398.939384] usb 2-3.3.1: Manufacturer: TerraMaster
[ 1398.939385] usb 2-3.3.1: SerialNumber: 202404120029
[ 1398.940600] usb-storage 2-3.3.1:1.0: USB Mass Storage device detected
[ 1398.940690] scsi host53: usb-storage 2-3.3.1:1.0
[ 1399.009809] usb 2-3.3.2: new SuperSpeed Plus Gen 2x1 USB device number 39 using xhci_hcd
[ 1399.022477] usb 2-3.3.2: New USB device found, idVendor=235c, idProduct=a006, bcdDevice= 1.00
[ 1399.022484] usb 2-3.3.2: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 1399.022485] usb 2-3.3.2: Product: TDAS
[ 1399.022487] usb 2-3.3.2: Manufacturer: TerraMaster
[ 1399.022488] usb 2-3.3.2: SerialNumber: 202404120029
[ 1399.023821] usb-storage 2-3.3.2:1.0: USB Mass Storage device detected
[ 1399.023974] scsi host54: usb-storage 2-3.3.2:1.0
[ 1399.091813] usb 2-3.3.3: new SuperSpeed Plus Gen 2x1 USB device number 40 using xhci_hcd
[ 1399.104627] usb 2-3.3.3: New USB device found, idVendor=235c, idProduct=a006, bcdDevice= 1.00
[ 1399.104633] usb 2-3.3.3: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 1399.104634] usb 2-3.3.3: Product: TDAS
[ 1399.104636] usb 2-3.3.3: Manufacturer: TerraMaster
[ 1399.104637] usb 2-3.3.3: SerialNumber: 202404120029
[ 1399.106192] usb-storage 2-3.3.3:1.0: USB Mass Storage device detected
[ 1399.106480] scsi host55: usb-storage 2-3.3.3:1.0
[ 1399.172330] scsi 51:0:0:0: Direct-Access TerraMas TDAS 0 PQ: 0 ANSI: 6
[ 1399.172481] sd 51:0:0:0: Attached scsi generic sg4 type 0
[ 1399.173215] sd 51:0:0:0: [sdy] Very big device. Trying to use READ CAPACITY(16).
[ 1399.173390] sd 51:0:0:0: [sdy] 7814037168 512-byte logical blocks: (4.00 TB/3.64 TiB)
[ 1399.173393] sd 51:0:0:0: [sdy] 4096-byte physical blocks
[ 1399.173666] sd 51:0:0:0: [sdy] Write Protect is off
[ 1399.173668] sd 51:0:0:0: [sdy] Mode Sense: 43 00 00 00
[ 1399.174004] sd 51:0:0:0: [sdy] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 1399.175749] usb 2-3.3.4: new SuperSpeed Plus Gen 2x1 USB device number 41 using xhci_hcd
[ 1399.179710] [292]: scst: scst_register_deviceAttached to scsi51, channel 0, id 0, lun 0, type 0
[ 1399.188367] usb 2-3.3.4: New USB device found, idVendor=235c, idProduct=a006, bcdDevice= 1.00
[ 1399.188372] usb 2-3.3.4: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[ 1399.188374] usb 2-3.3.4: Product: TDAS
[ 1399.188375] usb 2-3.3.4: Manufacturer: TerraMaster
[ 1399.188377] usb 2-3.3.4: SerialNumber: 202404120029
[ 1399.189901] usb-storage 2-3.3.4:1.0: USB Mass Storage device detected
[ 1399.189994] scsi host56: usb-storage 2-3.3.4:1.0
[ 1399.236753] sdy: sdy1 sdy2 sdy3 sdy4
[ 1399.236972] sd 51:0:0:0: [sdy] Attached SCSI disk
[ 1399.363442] scsi 52:0:0:0: Direct-Access TerraMas TDAS 0 PQ: 0 ANSI: 6
[ 1399.363541] sd 52:0:0:0: Attached scsi generic sg7 type 0
[ 1399.363570] [292]: scst: scst_register_deviceAttached to scsi52, channel 0, id 0, lun 0, type 0
[ 1399.364352] sd 52:0:0:0: [sdz] Very big device. Trying to use READ CAPACITY(16).
[ 1399.364471] sd 52:0:0:0: [sdz] 7814037168 512-byte logical blocks: (4.00 TB/3.64 TiB)
[ 1399.364473] sd 52:0:0:0: [sdz] 4096-byte physical blocks
[ 1399.364776] sd 52:0:0:0: [sdz] Write Protect is off
[ 1399.364780] sd 52:0:0:0: [sdz] Mode Sense: 43 00 00 00
[ 1399.365055] sd 52:0:0:0: [sdz] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 1399.412705] sdz: sdz1 sdz2 sdz3 sdz4
[ 1399.412841] sd 52:0:0:0: [sdz] Attached SCSI disk
[ 1400.003161] scsi 53:0:0:0: Direct-Access TerraMas TDAS 0 PQ: 0 ANSI: 6
[ 1400.003278] sd 53:0:0:0: Attached scsi generic sg8 type 0
[ 1400.003315] [292]: scst: scst_register_deviceAttached to scsi53, channel 0, id 0, lun 0, type 0
[ 1400.009510] sd 53:0:0:0: [sdaa] Very big device. Trying to use READ CAPACITY(16).
[ 1400.009664] sd 53:0:0:0: [sdaa] 11721045168 512-byte logical blocks: (6.00 TB/5.46 TiB)
[ 1400.009667] sd 53:0:0:0: [sdaa] 4096-byte physical blocks
[ 1400.009945] sd 53:0:0:0: [sdaa] Write Protect is off
[ 1400.009949] sd 53:0:0:0: [sdaa] Mode Sense: 43 00 00 00
[ 1400.010223] sd 53:0:0:0: [sdaa] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 1400.054855] sdaa: sdaa1 sdaa2 sdaa3 sdaa4
[ 1400.055236] sd 53:0:0:0: [sdaa] Attached SCSI disk
[ 1400.067010] scsi 54:0:0:0: Direct-Access TerraMas TDAS 0 PQ: 0 ANSI: 6
[ 1400.067153] sd 54:0:0:0: Attached scsi generic sg9 type 0
[ 1400.067191] [292]: scst: scst_register_deviceAttached to scsi54, channel 0, id 0, lun 0, type 0
[ 1400.067860] sd 54:0:0:0: [sdab] Very big device. Trying to use READ CAPACITY(16).
[ 1400.068110] sd 54:0:0:0: [sdab] 7814037168 512-byte logical blocks: (4.00 TB/3.64 TiB)
[ 1400.068112] sd 54:0:0:0: [sdab] 4096-byte physical blocks
[ 1400.068440] sd 54:0:0:0: [sdab] Write Protect is off
[ 1400.068443] sd 54:0:0:0: [sdab] Mode Sense: 43 00 00 00
[ 1400.068889] sd 54:0:0:0: [sdab] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 1400.111716] sdab: sdab1 sdab2 sdab3 sdab4
[ 1400.111872] sd 54:0:0:0: [sdab] Attached SCSI disk
[ 1400.131212] scsi 55:0:0:0: Direct-Access TerraMas TDAS 0 PQ: 0 ANSI: 6
[ 1400.131306] sd 55:0:0:0: Attached scsi generic sg10 type 0
[ 1400.131343] [292]: scst: scst_register_deviceAttached to scsi55, channel 0, id 0, lun 0, type 0
[ 1400.132074] sd 55:0:0:0: [sdac] Very big device. Trying to use READ CAPACITY(16).
[ 1400.132238] sd 55:0:0:0: [sdac] 7814037168 512-byte logical blocks: (4.00 TB/3.64 TiB)
[ 1400.132240] sd 55:0:0:0: [sdac] 4096-byte physical blocks
[ 1400.132516] sd 55:0:0:0: [sdac] Write Protect is off
[ 1400.132518] sd 55:0:0:0: [sdac] Mode Sense: 43 00 00 00
[ 1400.132798] sd 55:0:0:0: [sdac] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 1400.195088] scsi 56:0:0:0: Direct-Access TerraMas TDAS 0 PQ: 0 ANSI: 6
[ 1400.195204] sd 56:0:0:0: Attached scsi generic sg11 type 0
[ 1400.195240] [292]: scst: scst_register_deviceAttached to scsi56, channel 0, id 0, lun 0, type 0
[ 1400.196298] sdac: sdac1 sdac2 sdac3 sdac4
[ 1400.196453] sd 55:0:0:0: [sdac] Attached SCSI disk
[ 1400.201497] sd 56:0:0:0: [sdad] Very big device. Trying to use READ CAPACITY(16).
[ 1400.201725] sd 56:0:0:0: [sdad] 11721045168 512-byte logical blocks: (6.00 TB/5.46 TiB)
[ 1400.201728] sd 56:0:0:0: [sdad] 4096-byte physical blocks
[ 1400.202033] sd 56:0:0:0: [sdad] Write Protect is off
[ 1400.202035] sd 56:0:0:0: [sdad] Mode Sense: 43 00 00 00
[ 1400.202312] sd 56:0:0:0: [sdad] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 1400.246535] sdad: sdad1 sdad2 sdad3 sdad4
[ 1400.246720] sd 56:0:0:0: [sdad] Attached SCSI disk
[ 1420.938307] Buffer I/O error on dev md5, logical block 4869780464, async page read

and via mdadm --detail /dev/md4