Re: data checksums

> On Aug 6, 2024, at 19:45, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> wrote:
> I am surprised by that. Would you say that most storage systems will happily give you a
> garbage block if there was a hardware problem somewhere?

"Most" is hard for me to judge. HDDs can have uncorrected and undetected errors, definitely. ZFS, for example, can correct those (within limits); XFS doesn't try. I have been told that SSDs can have uncorrected/undetected errors as well, but I don't know details on that.

> Turning data checksums on will write WAL for hint bits, which can significantly increase
> the amount of WAL written.

I was curious about that, so I just did a quick experiment using pgbench, with identical databases except for checksums. They both generated the same amount of WAL within 10% or so, so I don't think the impact is huge. (And you need the hint bits for pg_rewind, which is a nice thing to have in your back pocket if required.)