Re: basic_archive lost archive_directory

Hello

How to reproduce:

1) configure

archive_mode = on
archive_library = 'basic_archive'
basic_archive.archive_directory = '/some/path/'

2) start postgres and verify archive works
3) make this directory temporary inaccessible. NFS will give you many ways to achieve this, here just mv /some/ /some_moved/  is enough.
4) basic_archive will complain ERROR:  could not create file ... No such file or directory for new WAL archive attempts
5) restart archiver process with any reason: kill it or restart postgres
6) make archive_directory accessible again: archiver process will not check the directory's existence again and continue to complain about unconfigured archive_directory

Maybe it makes sense to move the directory existence check from check_archive_directory (guc check callback) to basic_archive_configured? (attached)

regards, Sergei