This is an even better set of steps for reproducing the problem.
[root@srv]# sync
[root@srv]# mkdir /home/.snapshots/test1
[root@srv]# btrfs su sn -r /home/ /home/.snapshots/test1/
Create a readonly snapshot of '/home/' in '/home/.snapshots/test1//home'
[root@srv]# sync
[root@srv]# mkdir /mnt/x5a/home/test1
[root@srv]# btrfs send /home/.snapshots/test1/home/ | btrfs receive
/mnt/x5a/home/test1/
At subvol /home/.snapshots/test1/home/
At subvol home
[root@srv]# ls -la /mnt/x5a/home/test1/home/user1/
NOTE: all recent files are present
[root@srv]# ls -la /mnt/x5a/home/test1/home/user2/Documents/
NOTE: all recent files are present
[root@srv]# mkdir /home/.snapshots/test2
[root@srv]# mkdir /mnt/x5a/home/test2
[root@srv]# btrfs su sn -r /home/ /home/.snapshots/test2/
Create a readonly snapshot of '/home/' in '/home/.snapshots/test2//home'
[root@srv]# sync
[root@srv]# btrfs send -p /home/.snapshots/test1/home/
/home/.snapshots/test2/home/ | btrfs receive /mnt/x5a/home/test2/
At subvol /home/.snapshots/test2/home/
At snapshot home
[root@srv]# ls -la /mnt/x5a/home/test2/home/user1/
NOTE: all recent files are MISSING
[root@srv]# ls -la /mnt/x5a/home/test2/home/user2/Documents/
NOTE: all recent files are MISSING
Any ideas what could be causing this problem with incremental backups?
On Wed, Sep 6, 2017 at 3:23 PM, Dave <davestechs...@gmail.com> wrote:
>
> Here is more info on this problem. I can reproduce this without using my
> script. Simple btrfs commands will reproduce the problem every time. The same
> files are missing every time. There is no randomness to the missing data.
>
> Here are my steps:
>
> 1. snapper -c home create
> result is a valid snapshot at /home/.snapshots/1704/snapshot
> 2. btrfs send /home/.snapshots/1704/snapshot | btrfs receive
> /mnt/x5a/home/1704
> 3. snapper -c home create
> result is a valid snapshot at /home/.snapshots/1716/snapshot
> 4. btrfs send -c /home/.snapshots/1704/snapshot/
> /home/.snapshots/1716/snapshot/ | btrfs receive /mnt/x5a/home/1716/
>
> I expect /mnt/x5a/home/1716/snapshot to be identical to
> /home/.snapshots/1716/snapshot. However, it is not.
> The result is that /mnt/x5a/home/1716/snapshot is missing all recent files.
>
> Next step was to delete snapshot 1716 (in both locations) and repeat the send
> | receive using -p
>
> btrfs su del /mnt/x5a/home/1716/snapshot
> snapper -c home delete 1716
> snapper -c home create
> btrfs send -p /home/.snapshots/1704/snapshot/ /home/.snapshots/1716/snapshot/
> | btrfs receive /mnt/x5a/home/1716/
>
> The result is once again that /mnt/x5a/home/1716/snapshot is missing all
> recent files. However, the other snapshots are all valid:
> /home/.snapshots/1704/snapshot is valid & complete
> /mnt/x5a/home/1704/snapshot -- non-incremental send: snapshot is valid &
> complete
> /home/.snapshots/1716/snapshot is valid & complete
> /mnt/x5a/home/1716/snapshot -- incrementally sent snapshot is missing all
> recent files whether sent with -c or -p
>
> The incrementally sent snapshot is even missing files that are present in the
> reference snapshot /mnt/x5a/home/1704/snapshot.
>
>
>
> On Wed, Sep 6, 2017 at 1:37 AM, Dave <davestechs...@gmail.com> wrote:
>>
>> I'm running Arch Linux on BTRFS. I use Snapper to take hourly
>> snapshots and it works without any issues.
>>
>> I have a bash script that uses send | receive to transfer snapshots to
>> a couple external HDD's. The script runs daily on a systemd timer. I
>> set all this up recently and I first noticed that it runs every day
>> and that the expected snapshots are received.
>>
>> At a glance, everything looked correct. However, today was my day to
>> drill down and really make sure everything was working.
>>
>> To my surprise, the newest received incremental snapshots are missing
>> all recent files. These new snapshots reflect the system state from
>> weeks ago and no files more recent than a certain date are in the
>> snapshots.
>>
>> However, the snapshots are newly created and newly received. The work
>> is being done fresh each day when my script runs, but the results are
>> anchored back in time at this earlier date. Weird.
>>
>> I'm not really sure where to start troubleshooting, so I'll start by
>> sharing part of my script. I'm sure the problem is in my script, and
>> is not related to BTRFS or snapper functionality. (As I said, the
>> Snapper snapshots are totally OK before being sent | received.
>>
>> These are the key lines of the script I'm using to send | receive a snapshot:
>>
>> old_num=$(snapper -c "$config" list -t single | awk
>> '/'"$selected_uuid"'/ {print $1}')
>> old_snap=$SUBVOLUME/.snapshots/$old_num/snapshot
>> new_num=$(snapper -c "$config" create --print-number)
>> new_snap=$SUBVOLUME/.snapshots/$new_num/snapshot
>> btrfs send -c "$old_snap" "$new_snap" | $ssh btrfs receive
>> "$backup_location"
>>
>> I have to admit that even after reading the following page half a
>> dozen times, I barely understand the difference between -c and -p.
>> https://btrfs.wiki.kernel.org/index.php/FAQ#What_is_the_difference_between_-c_and_-p_in_send.3F
>>
>> After reading that page again today, I feel like I should switch to -p
>> (maybe). However, the -c vs -p choice probably isn't my problem.
>>
>> Any ideas what my problem could be?
>
>
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