this post was submitted on 19 May 2026
34 points (97.2% liked)

Selfhosted

59343 readers
788 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

  1. Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.

  2. No spam posting.

  3. Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.

  4. Don't duplicate the full text of your blog or github here. Just post the link for folks to click.

  5. Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).

  6. No trolling.

  7. No low-effort posts. This is subjective and will largely be determined by the community member reports.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 3 years ago
MODERATORS
 

I'm running a Ubuntu server on my old laptop with an external HDD connected to it. The external HDD is powered independently from the laptop, as it is plugged into the wall.

During a power outage, my laptop remains operational due to its battery, but the HDD shuts down. When power is restored, my laptop does not automatically remount the HDD, and I have to reboot the system manually to access it.

Does anyone know how I can resolve this issue?

Edit: Not sure if this added context changes anything, but this is the HDD I'm using. It's a 3.5" HDD that gets its power directly from the wall.

top 40 comments
sorted by: hot top controversial new old
[–] stardreamer@lemmy.blahaj.zone 4 points 2 hours ago

I feel like I'm taking crazy pills here. Isn't the correct solution to use udev rules?

[–] IpsumLauren@lemmy.world 5 points 5 hours ago* (last edited 5 hours ago)

Remove the laptop battery.

/jk

I used to have a similar setup and the disk didn't last a year. All those power losses are going to break the disk eventually. Now I'm trying a cheap UPS.

[–] Shimitar@downonthestreet.eu 4 points 6 hours ago (1 children)

In short: buy a cheap ups power strip or a generous USB powebank capable to being under charge 24/7 and do not let the HDD switch off on power loss...

That is a guaranteed recepy to destroy your data and possibly the hardware as well as spinning disks don't like abrupt shutoff and that applies to data being written on SSDs as well.

Remounting after the power resumes is the last of the issues, easily fixed by a amount/mount command with the proper fstab setup.

[–] Lenna@piefed.ca 1 points 3 hours ago (1 children)

Do you have a USB power bank you can recommend? My external HDD requires a wall plug and I've never seen a USB power bank where I could plug my HDD into it.

[–] Landless2029@lemmy.world 1 points 55 minutes ago* (last edited 54 minutes ago) (1 children)

You have a 3.5" based HDD (aka desktop drive). many people use 2.5" drives (laptop drives) since they get power from the PC with just usb

[–] Lenna@piefed.ca 1 points 37 minutes ago

So that means it's not possible for me to power my 3.5" HDD with just USB, right?

[–] irmadlad@lemmy.world 15 points 14 hours ago (3 children)

I had one back in the day like that. My notes on that event are old so maybe someone can modify or clarify.

First you'll have to find the UUID of the external drive. (lsblk -f) Then create a mount file like: sudo nano /etc/systemd/system/mnt-data.mount. In the mnt-data.mount file, insert something like:

[Unit]
Description=External HDD Mount
Requires=dev-disk-by\x2duuid-<YOUR_UUID>.device
After=dev-disk-by\x2duuid-<YOUR_UUID>.device
After=local-fs.target

[Mount]
What=/dev/disk/by-uuid/<YOUR_UUID>
Where=/mnt/data
Type=ext4  # Change to ntfs, xfs, etc., depending on your drive format
Options=rw,noatime,nofail

Enable and reload:

sudo systemctl daemon-reload
sudo systemctl enable mnt-data.mount
sudo systemctl start mnt-data.mount

Verify status:

systemctl status mnt-data.mount

Should say 'active'. Reboot and test. Let me know if that works. Like I said, that was a while ago. If it works, it's just another reason why you should doccument your server setups. If it doesn't, well shucks I tried. LOL

[–] IpsumLauren@lemmy.world 2 points 5 hours ago

TIL about systemd mounts, thanks!

[–] happy_wheels@lemmy.blahaj.zone 10 points 14 hours ago (2 children)

This but put the entries in /etc/fstab instead.

[–] feannag@sh.itjust.works 5 points 6 hours ago (1 children)

Wouldn't that just mount the HDD when the server boots? I think the issue is re-mounting it while the server remains up, hence the systemd service. But maybe I don't understand fstab fully.

I wanted to provide feedback for THIS part only. :) not for OPs issue. I would have responded to OPs post if that were the case....

[–] irmadlad@lemmy.world 2 points 13 hours ago

I'll make an addenda to my notes. Thanks.

[–] Lenna@piefed.ca 2 points 12 hours ago

My /etc/fstab file currently has the following:

UUID=412ea77a-96e1-427c-9f75-2aae2fe0dca1 /mnt/wd ext4 defaults 0 2

If I were to use the mnt-data.mount you've suggested, does that mean I need to delete what I already have in /etc/fstab and replace it with what you suggested?

[–] ohulancutash@feddit.uk 6 points 14 hours ago (1 children)

That risks breaking the drive eventually. They don’t handle loss of power well. And if its being written to at the time, data loss and corruption is inevitable.

That said, no need to reboot to mount the drive.

sudo mount -a
[–] Lenna@piefed.ca 1 points 11 hours ago (1 children)

I shall give this a try the next time it loses power. Thank you.

[–] OwOarchist@pawb.social 2 points 8 hours ago* (last edited 8 hours ago)

Then set up a cron job that periodically tries to read a file on the drive, and if that command fails, then execute sudo mount -a

Like, set up a root account cron job to run touch \external_drive\test_file.txt || mount -a at 5-minute intervals.

[–] Natanael@slrpnk.net 4 points 14 hours ago (2 children)

I recommend a UPS, even a small one is fine for this. Spinning disks don't like frequent starts and stops, especially not unplanned powerless ones.

At least you should be running a journaling file system or something similar which tolerates power loss decently (you'll still see data corruption, but the file system won't die). If you run software that doesn't tolerate power loss well, then you absolutely need an UPS

[–] Lenna@piefed.ca 1 points 29 minutes ago (1 children)

This is my HDD. Aren't these guys able to handle power losses since people usually plug them in to backup stuff, and then pull the plug once they're done?

And does ext4 count as a journaling file system?

[–] chris@l.roofo.cc 1 points 25 minutes ago

It's not good to power off a mounted drive. At least for the file system. I don't know about the drive itself.

[–] SpikesOtherDog@ani.social 1 points 14 hours ago

Find a used one for sale. Bonus points if it has any kind of management. Replace the battery. If at all possible, have it unmount the drive at a certain percentage.

[–] FreedomAdvocate@lemmy.net.au 0 points 7 hours ago (1 children)

First step is to not use a laptop with a charged/charging battery in it as an always-on server. Terrible idea.

[–] Lenna@piefed.ca 1 points 3 hours ago (1 children)

Could you please elaborate on why this is a bad idea?

[–] FreedomAdvocate@lemmy.net.au 1 points 3 hours ago (2 children)

Having a battery that is constantly charging and kept at 100% is bad for the battery. Very bad. Batteries don’t like heat, and being kept on and in use endlessly generates heat constantly. Batteries should be avoided for things like this as they can swell and/or explode.

[–] Natanael@slrpnk.net 1 points 58 minutes ago

This depends entirely on the motherboard because many newer ones are fully capable of disconnecting the battery and maintaining it intelligently like smartphones does

[–] CovfefeKills@lemmy.world 1 points 3 hours ago* (last edited 3 hours ago)

Chill bro they have BMS's. I keep my always plugged in laptop at 60% battery for this reason but they aren't infants you don't need to baby them.

[–] warmaster@lemmy.world 3 points 15 hours ago

I can infer that you want suggestions for cost efficient backup power. Depending on the laptop model, it could power the HDD and in case of an outage it could draw power from the laptop's battery. It would decrease battery charge duration but it would be enough for a graceful shutdown to prevent data loss.

Alternatively, you could maybe use a battery pack.

[–] tal@lemmy.today 1 points 14 hours ago* (last edited 12 hours ago) (1 children)

Does anyone know how I can resolve this issue?

I don't know why you'd need a reboot to remount the thing. Are you just not familiar with how to add something to /etc/fstab and mount it manually and are relying on some kind of auto-mounting system that only happens to run at boot, or is it giving some kind of error?

If an error, what happens when you do:

$ sudo mount -o remount /mnt/the-mount-point

?

[–] Lenna@piefed.ca 2 points 11 hours ago (2 children)

auto-mounting system that only happens to run at boot

This is correct. I made my drive auto mount using /etc/fstab, and I believe that is only checked once during boot.

[–] tofu@lemmy.nocturnal.garden 1 points 10 hours ago (1 children)

You can run mount -a to mount all fstab entries. You could put that in a cronjob I guess

[–] Lenna@piefed.ca 2 points 9 hours ago (1 children)

If I were to make it run that command every 5 minutes, would there be any downsides?

[–] tofu@lemmy.nocturnal.garden 1 points 8 hours ago

I don't know if it has side effects when there's issues with mounting or the like.

It would also interfere if you want to unmount it and forget to disable the cronjob.

[–] tal@lemmy.today 1 points 11 hours ago (1 children)

Nah, that's good. What I mean is, if it's in /etc/fstab, it should be possible to manually mount it without a reboot. Have you tried manually remounting it after power comes back?

[–] Lenna@piefed.ca 2 points 10 hours ago (1 children)

Nope, I haven't tried that. But I will give it a try when the next power outage occurs. I actually didn't know I could manually remount until today. I'm still pretty new to selfhosting.

[–] tal@lemmy.today 2 points 10 hours ago

Gotcha. Yeah, the stuff in fstab is just a convenience; it's equivalent to running a bunch of mount commands at boot. You might be able to just run "mount" again without the '-o remount" option. I was just listing that in case you were seeing some kind of errors in trying to manually mount it.

[–] AbidanYre@lemmy.world 1 points 15 hours ago* (last edited 15 hours ago) (2 children)

Autofs might do what you're looking for. How often do you have power outages that it's a major concern?

[–] Lenna@piefed.ca 1 points 10 hours ago

It doesn't happen often, but when it does happen I temporarily lose access to my media. But based on what others are saying here, it looks like it's possible to manually remount my drive instead of rebooting. So I'll give that a try.

[–] tal@lemmy.today 1 points 14 hours ago

I was going to mention that, but also that while I'm sure that it'd handle power loss while it's unmounted the filesystem I don't know what happens if the backing storage goes away while it's in use.

[–] Ebby@lemmy.ssba.com 1 points 15 hours ago (1 children)

Cheap and dirty solution would be a battery backup for the drive, but there are some big concerns about the setup. Drives don't like to go dark like that.

[–] Lenna@piefed.ca 1 points 15 hours ago (1 children)

I had a laptop lying around and computer parts are too expensive now to build my own server, so that's what I went with. Is the concern you have involving loss of data?

[–] Ebby@lemmy.ssba.com 2 points 14 hours ago

One concern, yes. Others such as parking heads. Don't want platters spinning down with drive heads hovering. Power spikes won't do the circuit boards any good.

Doesn't hurt to show servers some kindness even if it's a laptop in a closet.