Database Corruption (pihole-ftl.db)

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1

The issue I am facing: The database got corrupted (pihole-ftl.db)

Details about my system: Pi-Hole running on Pi Zero 2 W with Raspberry Pi OS 32 bit

What I have changed since installing Pi-hole: maxdbdays=1000 in pihole-FTL.conf and added 2 new adblock lists

More info: A week ago I have noticed that all my historical data was missing, the total domains on domains on adlists was showing 55 from 150K but everything was working just fine.
Since then I have added another Pi-Hole on another Raspberry Pi 4b and currently I am running both of them in parallel (2 entries in my router config).

2-3 times per week I do a full SD card backup (SD Card Copier), I have put the backup SD card but the problem persisted (I think I backed up with the corrupted DB).

Today I changed the Upstream DNS Servers settings in Settings > DNS from Quad9 filtered to Quad9 unfiltered hit Save and again, all my historical data for the last couple of days was gone.
This did not happen on the new Pi-Hole installation, only on the one running on Pi Zero 2 W.

I will attach both debug logs (from both Raspberry Pis):
https://tricorder.pi-hole.net/IhPBmjOc/ - Pi 4b - started using this 1-2 days ago
https://tricorder.pi-hole.net/abBCTTDs/ - Pi Zero 2 W with corrupted pihole-ftl.db (I presume)

My questions:

  • can I delete pihole-ftl.db? Will PiHole make a new one after a reboot?
  • Is there anything I can do to prevent this problem from occurring in the future?

Thank you,

1 Like
2

Yes.

You need to stop FTL, delete the database and restart FTL (no need to reboot). A new database will be created.

Run these commands:

sudo service pihole-FTL stop

sudo mv /etc/pihole/pihole-FTL.db /etc/pihole/pihole-FTL-old.db

sudo service pihole-FTL start
3

It's hard to suggest something here. We don't know what caused the corruption in your case.
Maybe a faulty SD card? Maybe a power failure? Or maybe something else.

If you are constantly seeing this kind of corruption, I suggest you to replace your SD card.

4

Thank you, did this now I'll have to wait and see.

When I set up my second Pi-Hole (Raspberry Pi 4b) I used the "Teleporter" function, so far so good, nothing broke. This new installation is running on a brand new SDCard so who knows, time will tell.

The important thing is that everything worked despite this issue. If it'll happen in the future, I'll just do these steps again and move to a USB3 SSD, out of curiosity.

Thank you again. :slight_smile:

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