I've seen bit-rot on a few disks out of hundreds used over the last
35-ish years.
I am now storing /var/lib/backuppc on a ZFS RAID since the last
catastophic disk failure. Sure enough one of those disks started writing
garbage and then was taken off-line through infant mortality. The pool
kept going. A year or so later a different disk went off-line, with a
dying SATA cable this time. The pool kept going. In both cases
rebuilding the array ("re-silvering") happened automagically.
Very happy with ZFS myself. YMMV.
Paul
On 06/03/2021 13:50, G.W. Haywood via BackupPC-users wrote:
> Hi there,
>
> On Sat, 6 Mar 2021, John Botha (SourceForge) wrote:
>
>> ... take the plunge with BackupPC, ... bit rot protection is key ...
>> ...
>> ... fragmentation ... how best to approach this with a combination
>> of rebalancing and scrubbing, or if there is another way or other
>> aspects to keep in mind.
>> ...
>> ... I thought it would be safest to use nodatacow, but then read
>> that doing so would also stop bit rot protection, so that's a real
>> bummer. Am I missing something, or do I have that right?
>> ...
>> ... have btrfs handle de/compression, as that would seem to involve
>> less time doing redundant calculations. Does that make sense?
>> ...
>> ... seen some flame wars around the use of btrfs.
>
> I don't want to add fuel to any flames.
>
> In my view you're making it more difficult for yourself than you need
> to (or indeed should do) if you're just starting out with BackupPC.
>
> My take on it is that you will have quite enough on your plate getting
> BackupPC bedded down - so it's doing what you want in your particular
> circumstances, and you're comfortable with that - without adding into
> the mix a whole bunch of variables which don't need to be variables.
>
> If 'bit rot' protection is key to you, then set up BackupPC to avoid
> any possibility of it happening, spend a few months (or perhaps years)
> making sure that it isn't happening, and worry about filesystem(s),
> and any quirks they may have, some other time.
>
> I personally have never seen any evidence of what I imagine might be
> called 'bit rot' because in my view if something like that's happening
> then the system is badly broken and it needs fixing. But I have seen
> plenty of damaged filesystems. When I have had experience of damaged
> filesystems, I believe it's fair to say that the newer the filesystem,
> the more difficult it has been to repair it. The first (and last!!!)
> ReiserFS I ever used failed catastrophically and was never recovered.
> I've recovered everything from DOS to EXT/2/3/4 systems, usually with
> little difficulty; I've never used BTRFS so I can't offer any comment
> on its repairability.
>
> Right now I use EXT4 almost exclusively, and there would have to be a
> really technologically disruptive development in filesystem capability
> (like an order of magnitude improvement in some performance metric) to
> encourage me even to consider changing to anything else. I don't care
> if anybody thinks I'm an old stick-in-the-mud, I just want it to work.
>
> The other day when I was out with one of my dogs I fell into chatting
> with a couple of other walkers. This particular dog is a difficult
> case from the rescue. One of the walkers said "you seem to have a
> calm aura about you". Of course that's necessary for these difficult
> rescue cases. I thanked her for the compliment although I didn't say
> "it's because I use BackupPC and EXT4" - which wouldn't have been too
> far from the truth.
>
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