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External USB hard-drive changing drive letter

rated 0 times [ 2] [ 0] / answers: 1 / hits: 2997 / 12 Months ago, mon, may 29, 2023, 3:21:18

I have a Seagate FreeAgent Go external USB hard drive that was mounted but mysteriously decided to reconnect itself:

Sep 30 15:07:06 feinman kernel: [243901.551604] usb 1-1.2: USB disconnect, device number 3

Sep 30 15:07:06 feinman kernel: [243901.553828] sd 6:0:0:0: [sdb] Synchronizing SCSI cache

Sep 30 15:07:06 feinman kernel: [243901.553893] sd 6:0:0:0: [sdb]  Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK

Sep 30 15:07:10 feinman kernel: [243905.336557] usb 1-1.2: new high-speed USB device number 4 using ehci_hcd

Sep 30 15:07:10 feinman kernel: [243905.431219] scsi7 : usb-storage 1-1.2:1.0

Sep 30 15:07:11 feinman kernel: [243906.427207] scsi 7:0:0:0: Direct-Access     Seagate  FreeAgent Go     0148 PQ: 0 ANSI: 4

Sep 30 15:07:11 feinman kernel: [243906.428303] sd 7:0:0:0: Attached scsi generic sg1 type 0

Sep 30 15:07:11 feinman kernel: [243906.430317] sd 7:0:0:0: [sdc] 625142447 512-byte logical blocks: (320 GB/298 GiB)

Sep 30 15:07:11 feinman kernel: [243906.430860] sd 7:0:0:0: [sdc] Write Protect is off

Sep 30 15:07:11 feinman kernel: [243906.430865] sd 7:0:0:0: [sdc] Mode Sense: 1c 00 00 00

Sep 30 15:07:11 feinman kernel: [243906.431386] sd 7:0:0:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA

Sep 30 15:07:11 feinman kernel: [243906.493674]  sdc: sdc1

Sep 30 15:07:11 feinman kernel: [243906.496109] sd 7:0:0:0: [sdc] Attached SCSI disk

It changed from sdb to sdc, causing a number of problems for me. What can I do to further track down the cause?

I thought it might be a problem with it sleeping but when I cat /sys/class/scsi_disk/6:0:0:0/allow_restart, I see that it's already 1.

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donurp

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3 Years ago

answered 12 Months ago herriail · Accepted Answer

If you need for whatever reason to access the device file (like /dev/sdb1), and not the mount point itself, you should be using UUID's instead of the more traditional "sd*" labels.

Type blkid to find what the labels of the drives are, for example the output may look like that:

/dev/sda3: UUID="e04c6aa5-4341-491f-8226-ddf79021115d" TYPE="ext3"

The device ID which will not change is then

/dev/disk/by-uuid/e04c6aa5-4341-491f-8226-ddf79021115d

You are guaranteed that the UUID is unique and specific. You can use it also in your fstab directly:

UUID=e04c6aa5-4341-491f-8226-ddf79021115d /data ext3 relatime,errors=remount-ro 0 1