I’ve got a QNAP NAS and two Linux servers. Whenever the power goes down, the UPS kicks in and shut downs the NAS and the Linux servers, all good. The servers + NAS are automatically started when the power comes back on line using WOL. All good.
The problem is that I have apps running using Docker which heavily rely on connections to the NAS. As the Linux servers boot quicker than the NAS, the mount points are not mounted, and thus everything falls apart. Even when I manually re-mount, it’s not propagated to the Docker instances. All mount points use NFS.
Currently, I just reboot the Linux servers manually, and then all works well.
Probably easiest would be to run a cron job to check the mounts every x minutes, and if they are not mounted, then just reboot. The only issue is that this may cause an infinite loop of reboots if e.g. the NAS has been turned off.
I could also install a monitoring solution, but I’ve seen so many options that I’m not sure which one to do. If it’s easier with a monitoring solution, I’d like the simplest one.
Best option is to delay docker startup until the mounts are ready.
Read systemd mounts and systemd dependencies.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I’ve seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| DNS | Domain Name Service/System |
| NAS | Network-Attached Storage |
| Plex | Brand of media server package |
3 acronyms in this thread; the most compressed thread commented on today has 9 acronyms.
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The absolute easiest and simplest would be to modify your grub config to have a longer timer on the boot menu, effectively delaying them until the NAS is up.
That doesn’t necessarily mean it’s the best option- there are ways to make the actual boot process wait for mounts, or to stagger the WOL signals, or the solutions others have mentioned. But changing grub is quick and easy.
Not sure how Docker behaves, but in a Stack/Compose file you can define volumes to use a specific driver, such as smb. E.g.:
volumes:
smb-calibre:
driver_opts:
type: "smb3"
device: "//mynas/ebooks/CalibreDB"
o: "ro,vers=3.1.1,addr=192.168.1.1,username=mbirth,password=secret,cache=loose,iocharset=utf8,noperm,hard"
So Docker will take care of mounting. Paired with restart: unless-stopped, all my Containers come back online just fine after an outage.
