ZFS vs btfrs

[Bill Ricker]

On Thu, Feb 24, 2022, 11:55 Ken D'Ambrosio <ken at jots.org> wrote:

> I use the btrfs-send (which, of course, is modeled after zfs-send)...
> except, I kinda don't.  And this isn't a dig at btrfs (or ZFS), but just
> paranoia: I'm afraid that, if there were corruption on the source FS,
> using a FS-specific/replicating tool to do the data transfer might bring
> over whatever corruption was on the source in the first place.


Not a merely theoretical concern. I saw this happen.

Our British cousins fielded the same application we did, but since their
geographically dispersed data centers were within the radius supported for
syncronous SAN replication , they opted for that from primary cluster to
Disaster cluster. We were replicating much further so used semantic
replication stateside $BigCorp (log forwarding for DB, file level for
normal volumes), even though it had a chance of losing the last transaction
in flight. The DB driver made an error and wrote garbage 🗑,  which
corrupted DB indices, DB panicked. SAN dutifully copied the block level
writes to alternate site, so that panicked also. Oopsie. They had to
restore Prod last backup onto UAT system (and recreate all logged
transactions... a day of market!) to return to service. It was a bad week.

I much prefer semantic (vs block/bit) replication.
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