Openldap backup restore

First of all you should be aware of slapcat's limitations:

For some backend types, your slapd(8) should not be running 
(at least, not in read-write mode) when you do this to ensure 
consistency of the database. It is always safe to run slapcat 
with the slapd-bdb(5), slapd-hdb(5), and slapd-null(5) backends. 

So you better pack that backup in /etc/init.d/ldap stop and /etc/init.d/ldap start as well.

Before restarting ldap in the restore procedure, you can dump the just loaded data to a temporary file and compare that to the LDIF file you just used as input. I am pretty sure the LDIF output for slapcat is sorted by Distinguished Names so a diff should exit with exit-code 0.

...
chown ldap:ldap *

slapcat -l /var/tmp/test.ldif
diff /var/tmp/test.ldif /backup/openldap/backup_ldap2.diff
if [ $? != 0 ] ; then
     echo 'differences found'
fi

/etc/init.d/ldap start

This of course assumes that slapcat is working correctly. If you do not trust that you should extract all data relevant to you, from the running DB with ldap_search_ext(), generate some output (dump or checksum) from that, and compare that with running the same code on the restored database (after starting ldap of course). That way you would notice if some data relevant to your usage is left out of the dump by slapcat (unlikely, but possible if it has a bug)