> -    $class->zfs_request($scfg, undef, 'destroy', '-r',
> "$scfg->{pool}/$zvol");
> +    open(STDERR, ">/tmp/zfslog.txt");
> +    eval {  $class->zfs_request($scfg, undef, 'destroy', '-r',
> "$scfg->{pool}/$zvol")};
> +    close STDERR;
We have special hooks in run_command to catch stderr.
So please catch this in zfs_request, using 'errfunc' ...