4

Initramfs on my Debian testing system is not able automatically load necessary kernel modules for external USB 3 HDD (Seagate Backup Plus 1T) if it was already plugged in when initramfs started. If I boot into initramfs shell, plug cable out and plug it back in, then device will show up and I will be able to mount it.

I don't need this device in initramfs, but /dev/ filesystem created by initramfs is passed to main OS, where I do need it. I have to plug cable out and in to make device usable.

How do I setup initramfs to settle this device? Or how do I tell main OS to walk through hardware buses and handle all devices that udev in initramfs missed?

Additional information

After I plug device off and on, two new modules are loaded:

# lsmod 
Module                  Size  Used by
uas                    24576  0
usb_storage            69632  1 uas

These modules are available in initramfs image:

# lsinitramfs /boot/initrd.img-4.6.0-1-amd64 |grep -E '(uas|usb-storage)'
lib/modules/4.6.0-1-amd64/kernel/drivers/usb/storage/usb-storage.ko
lib/modules/4.6.0-1-amd64/kernel/drivers/usb/storage/uas.ko

uname, dmesg and lsusb output after plugging device in:

# uname -a
Linux pingwin 4.6.0-1-amd64 #1 SMP Debian 4.6.4-1 (2016-07-18) x86_64 GNU/Linux
# dmesg
[   53.412599] usb 2-2: new SuperSpeed USB device number 2 using xhci_hcd
[   53.429652] usb 2-2: New USB device found, idVendor=0bc2, idProduct=ab24
[   53.429659] usb 2-2: New USB device strings: Mfr=2, Product=3, SerialNumber=1
[   53.429662] usb 2-2: Product: BUP Slim BK
[   53.429664] usb 2-2: Manufacturer: Seagate
[   53.429667] usb 2-2: SerialNumber: NA7K016V
[   53.455444] usbcore: registered new interface driver usb-storage
[   53.458787] scsi host6: uas
[   53.458962] usbcore: registered new interface driver uas
[   53.459440] scsi 6:0:0:0: Direct-Access     Seagate  BUP Slim BK      0302 PQ: 0 ANSI: 6
[   53.497569] sd 6:0:0:0: Attached scsi generic sg2 type 0
[   53.497586] sd 6:0:0:0: [sdb] Spinning up disk...
[   54.503950] ...ready
[   56.518071] sd 6:0:0:0: [sdb] 1953525167 512-byte logical blocks: (1.00 TB/932 GiB)
[   56.518077] sd 6:0:0:0: [sdb] 2048-byte physical blocks
[   56.687950] sd 6:0:0:0: [sdb] Write Protect is off
[   56.687960] sd 6:0:0:0: [sdb] Mode Sense: 4f 00 00 00
[   56.688242] sd 6:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[   56.699372]  sdb: sdb1
[   56.700399] sd 6:0:0:0: [sdb] Attached SCSI disk

# lsusb -v -d 0bc2:ab24

Bus 004 Device 002: ID 0bc2:ab24 Seagate RSS LLC 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               3.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0         9
  idVendor           0x0bc2 Seagate RSS LLC
  idProduct          0xab24 
  bcdDevice            1.00
  iManufacturer           2 Seagate
  iProduct                3 BUP Slim BK
  iSerial                 1 NA7K016V
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          121
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower               36mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         8 Mass Storage
      bInterfaceSubClass      6 SCSI
      bInterfaceProtocol     80 Bulk-Only
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               0
        bMaxBurst              15
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               0
        bMaxBurst              15
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       1
      bNumEndpoints           4
      bInterfaceClass         8 Mass Storage
      bInterfaceSubClass      6 SCSI
      bInterfaceProtocol     98 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               0
        bMaxBurst              15
        MaxStreams             32
        Data-in pipe (0x03)
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               0
        bMaxBurst              15
        MaxStreams             32
        Data-out pipe (0x04)
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               0
        bMaxBurst              15
        MaxStreams             32
        Status pipe (0x02)
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x04  EP 4 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0400  1x 1024 bytes
        bInterval               0
        bMaxBurst               0
        Command pipe (0x01)
Binary Object Store Descriptor:
  bLength                 5
  bDescriptorType        15
  wTotalLength           22
  bNumDeviceCaps          2
  USB 2.0 Extension Device Capability:
    bLength                 7
    bDescriptorType        16
    bDevCapabilityType      2
    bmAttributes   0x00000002
      Link Power Management (LPM) Supported
  SuperSpeed USB Device Capability:
    bLength                10
    bDescriptorType        16
    bDevCapabilityType      3
    bmAttributes         0x00
    wSpeedsSupported   0x000e
      Device can operate at Full Speed (12Mbps)
      Device can operate at High Speed (480Mbps)
      Device can operate at SuperSpeed (5Gbps)
    bFunctionalitySupport   1
      Lowest fully-functional device speed is Full Speed (12Mbps)
    bU1DevExitLat          10 micro seconds
    bU2DevExitLat        2047 micro seconds
Device Status:     0x000c
  (Bus Powered)
  U1 Enabled
  U2 Enabled

udevadm output on initramfs and working system (they are pretty much the same, the only differences are in stat, iodone_cnt, ioerr_cnt, iorequest_cnt and urbnum):

# udevadm info -a -p /sys/block/sdb on initramfs


Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6/target6:0:0/6:0:0:0/block/sdb':
    KERNEL=="sdb"
    SUBSYSTEM=="block"
    DRIVER==""
    ATTR{alignment_offset}=="0"
    ATTR{badblocks}==""
    ATTR{capability}=="50"
    ATTR{discard_alignment}=="0"
    ATTR{events}==""
    ATTR{events_async}==""
    ATTR{events_poll_msecs}=="-1"
    ATTR{ext_range}=="256"
    ATTR{inflight}=="       0        0"
    ATTR{range}=="16"
    ATTR{removable}=="0"
    ATTR{ro}=="0"
    ATTR{size}=="1953525167"
    ATTR{stat}=="      72        0     4254      232        0        0        0        0        0      136      232"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6/target6:0:0/6:0:0:0':
    KERNELS=="6:0:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS=="sd"
    ATTRS{device_blocked}=="0"
    ATTRS{device_busy}=="0"
    ATTRS{dh_state}=="detached"
    ATTRS{eh_timeout}=="10"
    ATTRS{evt_capacity_change_reported}=="0"
    ATTRS{evt_inquiry_change_reported}=="0"
    ATTRS{evt_lun_change_reported}=="0"
    ATTRS{evt_media_change}=="0"
    ATTRS{evt_mode_parameter_change_reported}=="0"
    ATTRS{evt_soft_threshold_reached}=="0"
    ATTRS{inquiry}==""
    ATTRS{iocounterbits}=="32"
    ATTRS{iodone_cnt}=="0x7a"
    ATTRS{ioerr_cnt}=="0x8"
    ATTRS{iorequest_cnt}=="0x7a"
    ATTRS{model}=="BUP Slim BK     "
    ATTRS{queue_depth}=="30"
    ATTRS{queue_type}=="simple"
    ATTRS{rev}=="0302"
    ATTRS{scsi_level}=="7"
    ATTRS{state}=="running"
    ATTRS{timeout}=="30"
    ATTRS{type}=="0"
    ATTRS{vendor}=="Seagate "
    ATTRS{vpd_pg80}==""
    ATTRS{vpd_pg83}==""
    ATTRS{wwid}=="naa.5000000000000001"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6/target6:0:0':
    KERNELS=="target6:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6':
    KERNELS=="host6"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0':
    KERNELS=="4-2:1.0"
    SUBSYSTEMS=="usb"
    DRIVERS=="uas"
    ATTRS{authorized}=="1"
    ATTRS{bAlternateSetting}==" 1"
    ATTRS{bInterfaceClass}=="08"
    ATTRS{bInterfaceNumber}=="00"
    ATTRS{bInterfaceProtocol}=="62"
    ATTRS{bInterfaceSubClass}=="06"
    ATTRS{bNumEndpoints}=="04"
    ATTRS{supports_autosuspend}=="0"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2':
    KERNELS=="4-2"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{authorized}=="1"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bDeviceClass}=="00"
    ATTRS{bDeviceProtocol}=="00"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bMaxPacketSize0}=="9"
    ATTRS{bMaxPower}=="144mA"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{bcdDevice}=="0100"
    ATTRS{bmAttributes}=="80"
    ATTRS{busnum}=="4"
    ATTRS{configuration}==""
    ATTRS{devnum}=="2"
    ATTRS{devpath}=="2"
    ATTRS{idProduct}=="ab24"
    ATTRS{idVendor}=="0bc2"
    ATTRS{ltm_capable}=="no"
    ATTRS{manufacturer}=="Seagate"
    ATTRS{maxchild}=="0"
    ATTRS{product}=="BUP Slim BK"
    ATTRS{quirks}=="0x0"
    ATTRS{removable}=="removable"
    ATTRS{serial}=="NA7K016V"
    ATTRS{speed}=="5000"
    ATTRS{urbnum}=="371"
    ATTRS{version}==" 3.00"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4':
    KERNELS=="usb4"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{authorized}=="1"
    ATTRS{authorized_default}=="1"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bDeviceClass}=="09"
    ATTRS{bDeviceProtocol}=="03"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bMaxPacketSize0}=="9"
    ATTRS{bMaxPower}=="0mA"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{bcdDevice}=="0406"
    ATTRS{bmAttributes}=="e0"
    ATTRS{busnum}=="4"
    ATTRS{configuration}==""
    ATTRS{devnum}=="1"
    ATTRS{devpath}=="0"
    ATTRS{idProduct}=="0003"
    ATTRS{idVendor}=="1d6b"
    ATTRS{interface_authorized_default}=="1"
    ATTRS{ltm_capable}=="no"
    ATTRS{manufacturer}=="Linux 4.6.0-1-amd64 xhci-hcd"
    ATTRS{maxchild}=="4"
    ATTRS{product}=="xHCI Host Controller"
    ATTRS{quirks}=="0x0"
    ATTRS{removable}=="unknown"
    ATTRS{serial}=="0000:00:14.0"
    ATTRS{speed}=="5000"
    ATTRS{urbnum}=="47"
    ATTRS{version}==" 3.00"

  looking at parent device '/devices/pci0000:00/0000:00:14.0':
    KERNELS=="0000:00:14.0"
    SUBSYSTEMS=="pci"
    DRIVERS=="xhci_hcd"
    ATTRS{broken_parity_status}=="0"
    ATTRS{class}=="0x0c0330"
    ATTRS{consistent_dma_mask_bits}=="64"
    ATTRS{d3cold_allowed}=="1"
    ATTRS{device}=="0x1e31"
    ATTRS{dma_mask_bits}=="64"
    ATTRS{driver_override}=="(null)"
    ATTRS{enable}=="1"
    ATTRS{irq}=="29"
    ATTRS{local_cpulist}=="0-3"
    ATTRS{local_cpus}=="0f"
    ATTRS{msi_bus}=="1"
    ATTRS{numa_node}=="-1"
    ATTRS{subsystem_device}=="0x1949"
    ATTRS{subsystem_vendor}=="0x103c"
    ATTRS{vendor}=="0x8086"

  looking at parent device '/devices/pci0000:00':
    KERNELS=="pci0000:00"
    SUBSYSTEMS==""
    DRIVERS==""
# udevadm info -a -p /sys/block/sdb on booted system

Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6/target6:0:0/6:0:0:0/block/sdb':
    KERNEL=="sdb"
    SUBSYSTEM=="block"
    DRIVER==""
    ATTR{alignment_offset}=="0"
    ATTR{badblocks}==""
    ATTR{capability}=="50"
    ATTR{discard_alignment}=="0"
    ATTR{events}==""
    ATTR{events_async}==""
    ATTR{events_poll_msecs}=="-1"
    ATTR{ext_range}=="256"
    ATTR{inflight}=="       0        0"
    ATTR{range}=="16"
    ATTR{removable}=="0"
    ATTR{ro}=="0"
    ATTR{size}=="1953525167"
    ATTR{stat}=="      72        0     4254      328        0        0        0        0        0      272      328"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6/target6:0:0/6:0:0:0':
    KERNELS=="6:0:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS=="sd"
    ATTRS{device_blocked}=="0"
    ATTRS{device_busy}=="0"
    ATTRS{dh_state}=="detached"
    ATTRS{eh_timeout}=="10"
    ATTRS{evt_capacity_change_reported}=="0"
    ATTRS{evt_inquiry_change_reported}=="0"
    ATTRS{evt_lun_change_reported}=="0"
    ATTRS{evt_media_change}=="0"
    ATTRS{evt_mode_parameter_change_reported}=="0"
    ATTRS{evt_soft_threshold_reached}=="0"
    ATTRS{inquiry}==""
    ATTRS{iocounterbits}=="32"
    ATTRS{iodone_cnt}=="0xd1"
    ATTRS{ioerr_cnt}=="0x48"
    ATTRS{iorequest_cnt}=="0xd1"
    ATTRS{model}=="BUP Slim BK     "
    ATTRS{queue_depth}=="30"
    ATTRS{queue_type}=="simple"
    ATTRS{rev}=="0302"
    ATTRS{scsi_level}=="7"
    ATTRS{state}=="running"
    ATTRS{timeout}=="30"
    ATTRS{type}=="0"
    ATTRS{vendor}=="Seagate "
    ATTRS{vpd_pg80}==""
    ATTRS{vpd_pg83}==""
    ATTRS{wwid}=="naa.5000000000000001"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6/target6:0:0':
    KERNELS=="target6:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0/host6':
    KERNELS=="host6"
    SUBSYSTEMS=="scsi"
    DRIVERS==""

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2/4-2:1.0':
    KERNELS=="4-2:1.0"
    SUBSYSTEMS=="usb"
    DRIVERS=="uas"
    ATTRS{authorized}=="1"
    ATTRS{bAlternateSetting}==" 1"
    ATTRS{bInterfaceClass}=="08"
    ATTRS{bInterfaceNumber}=="00"
    ATTRS{bInterfaceProtocol}=="62"
    ATTRS{bInterfaceSubClass}=="06"
    ATTRS{bNumEndpoints}=="04"
    ATTRS{supports_autosuspend}=="0"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4/4-2':
    KERNELS=="4-2"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{authorized}=="1"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bDeviceClass}=="00"
    ATTRS{bDeviceProtocol}=="00"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bMaxPacketSize0}=="9"
    ATTRS{bMaxPower}=="144mA"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{bcdDevice}=="0100"
    ATTRS{bmAttributes}=="80"
    ATTRS{busnum}=="4"
    ATTRS{configuration}==""
    ATTRS{devnum}=="2"
    ATTRS{devpath}=="2"
    ATTRS{idProduct}=="ab24"
    ATTRS{idVendor}=="0bc2"
    ATTRS{ltm_capable}=="no"
    ATTRS{manufacturer}=="Seagate"
    ATTRS{maxchild}=="0"
    ATTRS{product}=="BUP Slim BK"
    ATTRS{quirks}=="0x0"
    ATTRS{removable}=="removable"
    ATTRS{serial}=="NA7K016V"
    ATTRS{speed}=="5000"
    ATTRS{urbnum}=="592"
    ATTRS{version}==" 3.00"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb4':
    KERNELS=="usb4"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{authorized}=="1"
    ATTRS{authorized_default}=="1"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bDeviceClass}=="09"
    ATTRS{bDeviceProtocol}=="03"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bMaxPacketSize0}=="9"
    ATTRS{bMaxPower}=="0mA"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{bcdDevice}=="0406"
    ATTRS{bmAttributes}=="e0"
    ATTRS{busnum}=="4"
    ATTRS{configuration}==""
    ATTRS{devnum}=="1"
    ATTRS{devpath}=="0"
    ATTRS{idProduct}=="0003"
    ATTRS{idVendor}=="1d6b"
    ATTRS{interface_authorized_default}=="1"
    ATTRS{ltm_capable}=="no"
    ATTRS{manufacturer}=="Linux 4.6.0-1-amd64 xhci-hcd"
    ATTRS{maxchild}=="4"
    ATTRS{product}=="xHCI Host Controller"
    ATTRS{quirks}=="0x0"
    ATTRS{removable}=="unknown"
    ATTRS{serial}=="0000:00:14.0"
    ATTRS{speed}=="5000"
    ATTRS{urbnum}=="47"
    ATTRS{version}==" 3.00"

  looking at parent device '/devices/pci0000:00/0000:00:14.0':
    KERNELS=="0000:00:14.0"
    SUBSYSTEMS=="pci"
    DRIVERS=="xhci_hcd"
    ATTRS{broken_parity_status}=="0"
    ATTRS{class}=="0x0c0330"
    ATTRS{consistent_dma_mask_bits}=="64"
    ATTRS{d3cold_allowed}=="1"
    ATTRS{device}=="0x1e31"
    ATTRS{dma_mask_bits}=="64"
    ATTRS{driver_override}=="(null)"
    ATTRS{enable}=="1"
    ATTRS{irq}=="29"
    ATTRS{local_cpulist}=="0-3"
    ATTRS{local_cpus}=="0f"
    ATTRS{msi_bus}=="1"
    ATTRS{numa_node}=="-1"
    ATTRS{subsystem_device}=="0x1949"
    ATTRS{subsystem_vendor}=="0x103c"
    ATTRS{vendor}=="0x8086"

  looking at parent device '/devices/pci0000:00':
    KERNELS=="pci0000:00"
    SUBSYSTEMS==""
    DRIVERS==""
# /etc/udev/udev.conf (the same on booted system and in initramfs)
# see udev.conf(5) for details
#
# udevd is started in the initramfs, so when this file is modified the
# initramfs should be rebuilt.

#udev_log="info"

It doesn't matter if I plug disk into USB 3 or USB 2 port on computer.

USB2 devices plugged in before initramfs initialization are correctly recognized and settled. I don't have any other USB 3 device to verify if it would be affected as well. However, I could try with this disk on my friend's computer (with Ubuntu 16.04) - it was settled and available in /dev/ after boot.

It doesn't matter if I generate initramfs by initramfs-tools or by dracut.

How can I ensure that /dev/sdb* related to this HDD is available in fully-booted system even if cable was plugged in before boot?

  • Do you have /etc/udev/udev.conf inside initramfs? (to allow for udev rules in there). And what is the output of udev info -a -p /sys/block/sdb within and outside of initramfs (when the device is there that is). – grochmal Jul 31 '16 at 19:46
  • @grochmal Yes, /etc/udev/udev.conf exists in initramfs, but it's as good as none. Added to question. I have also added udevadm info output from initramfs (after plug out and in) and booted system, although they are pretty much the same. – Mirosław Zalewski Jul 31 '16 at 20:15
2

OK, this is a wild guess and a workaround (rather than a proper understanding of the issue) but it should work.

Make a udev rules file, say, /etc/udev/rules.d/z30-seagate-disk.rules and add the following rule:

ATTRS{manufacturer}=="Seagate", ATTRS{product}=="BUP Slim BK", SYMLINK+="seagate"

This should force udev to make a second pass and add the disk as /dev/seagate block device. You will also need to add that file to the FILES variable in /etc/mkinitcpio.conf so it gets into the initramfs. (And run mkinitcpio -p linux to rebuild the initramfs)

Disclaimer: Tested on Arch, not on Debian, and not using USB 3.0.


Another workaround would be to force uas (USB SCSI) to be always loaded by the kernel. Add to a file say /etc/modules-load.d/seagate-disk.conf the module name:

uas
usb_storage
usbcore
scsi_mod
usb_common

In theory only uas is needed, but I cannot replicate you issue therefore I'd try brute forcing everything that is needed to manage a USB HDD. Again, add that file to FILES in /etc/mkinitcpio.conf.

This will force the kernel to have uas always loaded. Maybe while udev is running though the buses it falsely assumes the the USB hubs/buses are not loaded with anything since the kernel has no USB modules loaded.

  • Unfortunately, it did not work. Neither /dev/seagate nor /dev/sdb* was available in initramfs or booted system. I could find z30-seagate-disk.rules file in /lib/udev/rules.d/ in initramfs shell, so it was configured properly. – Mirosław Zalewski Jul 31 '16 at 22:35
  • @MirosławZalewski - hmm... I bet on some small inconsistency between uas and udev. I added another possible hack into the answer to get around it, not tested through. – grochmal Jul 31 '16 at 22:50
  • Thanks for a tip. However, it did not help. I managed to force-load module and it shows as loaded when I do lsmod in initramfs. But disk still does not show in /dev/... – Mirosław Zalewski Aug 2 '16 at 16:23
  • @MirosławZalewski - I figured out I do have a machine running kernel 4.6 (Arch not Debian though) and I do have a Seagate HDD too. I tried to replicate your problem on that setup but without success, my disk appears in /dev if I connect it to the machine before booting it. The only big difference on my machine is that all usb and scsi modules are loaded when the machine boots. As a last resort I'd try brute forcing all modules that are needed to operate a USB HDD to be loaded at boot. It is worth a try. – grochmal Aug 3 '16 at 16:41
  • As closing comment: right now this issue is mostly settled, that is external HDD is recognized about 9 out of 10 boots. It seems that reboots have higher chance of leaving disk in unrecognized state. I am hesitant to say that this is hardware problem (for reasons that I can't elaborate in comment), but I think that I have exhausted all software means of solving this. My drive did not work in the past and it seems to work now. I am going to accept your answer as it was most helpful; however I don't consider this issue truly solved yet. – Mirosław Zalewski Aug 9 '16 at 18:29
2

Edit /etc/modules and add a line containing uas.

Then run update-initramfs (e.g. update-initramfs -u -k $(uname -r) to update the initramfs for the currently running kernel. or -k all for all installed kernels).

Modules listed in /etc/modules are loaded automatically regardless of whether udev or anything else detects that they are needed.

This is also useful if you need or want to force a specific order for modules to be loaded, so that module foo will always be loaded before module bar (unless, of course, an earlier loaded module depends on bar).

As with any modules loaded by modprobe, you can set load time options in a file in /etc/modprobe.d/.

e.g. I have spl and zfs listed in /etc/modules, and /etc/modprobe.d/zfs.conf contains:

# use minimum 4GB and maxmum of 8GB RAM for ZFS ARC
options zfs zfs_arc_min=4294967296 zfs_arc_max=8589934592

If you want to know what load-time options a module knows, use modinfo [module] | grep parm. Module uas has none.

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