How to make filesystem name persistent - Filesystem name changes after re-plug/reboot

Software SW help
1

The following happens each time I re-plug my external USB HDDs:

The drives that I frequently unplug and re-plug, the filesystem names (is that even the correct term for it?) keep changing around. This time hdd6 is sdi1, next time it’s sdd1. I want these names to be fixed.

I searched the web and found out that there is udevadm on the turris OS. I get this, however, when trying to us it:

root@turris:~# udevadm info --path=/dev/sdi1 --query=all
device path not found
root@turris:~#

I assume I am not using it right.

Any help and pointers are much appreciated.

Or maybe there is even a different approach to solving this problem and making the names persistent?

2

Hey,

have you checked this out? I would recommend add another line to the /etc/fstab:
/dev/sdi1 /<path_to>/<mount_folder> ext4 defaults,nofail 0 2

EDIT: Please follow @horada’s post. And https://wiki.openwrt.org/doc/uci/fstab might come in handy.

3

For this kind of task is /etc/fstab the right place on common linux machine, but on Turris OS (or any OpenWRT) is the right place in /etc/config/fstab (the /etc/fstab is auto generated from this config file).
You have two options:

  1. configure it from Luci web interface (System -> Mount Points, section Mount Points)
  2. configure it in /etc/config/fstab similarly to this:
config mount
	option uuid 'aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee'
	option target '/mnt/data1'
	option enabled '1'
	option fstype 'ext4'

The uuid is from blkid command output, you can similarly use label.
It is not good idea to use just device name (like /dev/sda1) because this might change after reboot.

1 Like
4

I think you misunderstood me and the problem I want to solve: Like you say here, I want to prevent the system from changing the filesystem name in the /dev/ directory since I need them to be fixed after I unplug and replug the device or reboot the router. I want to setup routine tasks that depend on the name of the drive in /dev/ .

I have my drives setup like this:

config mount
        option target '/mnt/hdd1'
        option device '/dev/sdc1'
        option uuid '1bc37c49-0682-4491-9548-bea1f89c2e1c'
        option enabled_fsck '1'
        option enabled '1'

config mount
        option target '/mnt/hdd2'
        option device '/dev/sdd'
        option uuid '512dac84-6a1a-4314-a762-31d4a5e4befa'
        option enabled_fsck '1'
        option enabled '1'

Maybe this question is too trivial to ask and clear to the simplest of simplest linux user… :sweat:

6

Ah, ok I probably misunderstood it.
I thought that you need to heave always the same disk mounted to the particular /mnt/... directory. (If it is the case) then I would try to remove the lines option device '/dev/... from your configuration (to ensure that the disk will be “addressed” by the UUID and not by the “always changing” path in /dev/.
But if you really need to have the same device name (like /dev/sdc) for the particular physical device, then I’m not sure about the right solution for Turris OS/OpenWRT (AFAIK for normal desktop/server Linux distribution you will have to create your own custom udev rule for that, but I’m not sure if this apply also for TurrisOS/OpenWRT).

7

Yes, I added the /dev/ line just now to test weather or not the system would assign the path after remounting. It did not work.

Well, I need it for my convenience when addressing the drive from within the console, I don’t want to look up the /dev/ path each time, and for fixed tasks like smartmontool for those drives that get un- and replugged or after a reboot.

I was thinking custom udev rules as well, but I was not able to extract the device information bits for writing specific rules for each drive since the turris OS does not have the typical linux commands for doing it.

8

Yep I understood.
I found following doc: https://wiki.openwrt.org/doc/techref/hotplug
But I’m not 100% sure how this work on TurrisOS, so I’m not sure if the article is applicable for you. Maybe somebody else will have better information.

1 Like
9

I don’t know what this refers to exactly, yet, but I think this

https://wiki.archlinux.org/index.php/Udev#Setting_static_device_names

may be more the solution I need. I just found it by skimming over the article you refer to. @Koleon thanks for pointing it out.

10

Alright, now I understand, what you want to achieve :slight_smile:
Look at this and that article and focus on /dev/disk/by-id. Unfortunately I cannot experiment with that right now. Nevertheless I think you gonna need add a line (in fstab format) similar to the:
/dev/disk/by-id/scsi-3600605b000db099011b1713421c457ad-part2 /mnt/data1 ext4 acl,user_xattr 0 1

At first plug the HDD in and check by-id: $ ls -l /dev/disk/by-id It suppose to be possible check by-* whatever (by-id, by-label, by-uuid, by-path)
And then let’s try to rewrite it into the uci syntax as horada already pointed out.

config mount
	option by-id '3600605b000db099011b1713421c457ad-part2'
	option target '/mnt/data1'
	option enabled '1'
	option fstype 'ext4'

Even though I’m little bit sceptical because of the option by-id is not listed in the table at https://wiki.openwrt.org/doc/uci/fstab#mounting_filesystem give it a try. Hopefully it will work. :slight_smile:

1 Like
11

Ok, I dabbled with udev, but it does not seem to implement any options I am throwing at it through its config files.

Any more help would be much appreciated.