Backing up laptop with btrfs, what is OK and are there any simple steps?

[pavinjoseph]

@karlmistelberger

A full balance without filtering reallocates all chunks and is indeed a great sanity check

I would suggest a full rebalance only if the unmounted system shows no btrfs check errors. I think the defrag/rebalance caused my precarious filesystem to implode last time with quota/qgroup enabled.

[btr]

@pavinjoseph

@btr

btrfs check --check-data-csum --force /dev/sda2

That’s essentially what scrub does.

From man 8 btrfs-check:

       --check-data-csum
              verify checksums of data blocks

              This expects that the filesystem is otherwise OK, and is basically an offline scrub that does not repair data from spare copies.

Yes I saw that but it looks like btrfs check is doing several other tests even while running readonly:

[1/7] checking root items
[2/7] checking extents
[3/7] checking free space tree
[4/7] checking fs roots
[5/7] checking csums against data
[6/7] checking root refs
[7/7] checking quota groups
found 16308822016 bytes used, no error found

Isn’t this telling me file system is OK ?

[karlmistelberger]

@btr

Isn’t this telling me file system is OK ?

This doesn’t tell you anything! From: Infamous Host erlangen - #4 by karlmistelberger

“Metadata are perfectly consistent … However data are rotten as exposed by the numerous errors in the journal.”

[pavinjoseph]

Hmm, so can we conclude:

1. For verifying integrity of btrfs internals: btrfs check
2. For verifying integrity of data: btrfs scrub

[karlmistelberger]

Yep. These are the minimal read-only requirements.

• During prolonged operation btrfs maintenance services will run in the background.

• Users moving their system to btrfs may check their drives by performing read/write maintenance procedures in advance of the move, e.g. btrfs balance, btrfs device remove.

• Using btrfs on shaky hardware or system will eat up the benefit of the filesystem. This is a warrant.

[btr]

@pavinjoseph

• For verifying integrity of btrfs internals: btrfs check
• For verifying integrity of data: btrfs scrub

Sorry I’m a little confused here, are these the suitable commands to verify my clonezilla image/restore image adventures, right ?

[pavinjoseph]

@btr

Sorry I’m a little confused here, are these the suitable commands to verify my clonezilla image/restore image adventures, right ?

In most cases it should be enough.
But just to be extra sure, run a full rebalance on the restored image as well, since this can be considered as a write stress test, last time someone used clonezilla with partclone (?) it didn’t go well, their problems started surfacing when running balance.

[btr]

Thank you all who responded, great community for sure!

Alas, I have decided TBW is not for me at the moment and will leave this as it is.

There never was consistent behavior by btrfs (or more likely I didn’t figure out how to make it so). Also several updates killed the wifi on my macbook and although “snapper rollback” worked great I spent to much time fiddling with the system.

Cheers !