Dimitri Nagiev <dnagiev(at)gmx(dot)de> writes:
> using pg_dump I get the following error message:
> pg_dump: ERROR: cannot read block 1055 of summary: Input/output error
> calls from psql give me similar trouble:
> ERROR: cannot read block 1055 of summary: Interrupted system call
> There's a good backup from yesterday, but still I am very concerned.
As you should be. It sounds like your disk has developed a bad sector.
I'd recommend replacing the disk --- where one sector has gone bad,
others may soon follow.
regards, tom lane