Hi there,
On Wed, 21 Feb 2024, Alexander Kobel wrote:
February 18, 2024 at 9:52 AM, Christian V?lker wrote:
>
> I have a large v4 pool (not cpool) (1.6TB) running on top of btrfs.
For the record, that isn't a large pool for BackupPC to manage.
> Is there any chance to perform a pool check from BackupPC to verify
> all data in the pool is still ok? I am getting some checksum errors
> from btrfs and I want to know if the backed up data is still fine.
`dmesg` will show you where the checksum errors occur. ...
...
Unfortunately, it is non-trivial and time-consuming to find where a
file/hash from the pool is referenced in backups. ...
If you have filesystem errors then you really can't depend on it. If
this were my filesystem I'd completely replace it. But then there are
other people, not just me, depending on those backups.
Last time we had a serious filesystem error like this was about twenty
years ago, when unfortunately I was wooed by the promises of ReiserFS.
It lasted about a week, until it unrecoverably ate a test filesystem.
The provided fsck made it worse, I ditched it and went back to ext3.
If you need your backups, don't accept anything less than perfection.
Do the supplied btrfs tools not fix the errors?
https://en.wikipedia.org/wiki/Btrfs#Checking_and_recovery
https://en.wikipedia.org/wiki/Btrfs#Checksum_tree_and_scrubbing
Note that for some of the recovery operations you're expected to be,
or to be advised by, "a developer or an experienced user" of btrfs.
If you are not, perhaps btrfs isn't for you. I wouldn't yet trust it
with my backups.
Is this USB-connected hardware? If so, be very careful with it; I'd
be inclined to run at least two backup systems, perhaps running them
alternately. I'm not sure that USB is safe for backups, and I'm not
sure that btrfs is a good choice anyway.
Do you have uninterruptible power on the backup system?
--
73,
Ged.
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