"threads" directive OpenLDAP 2.0.* & 2.1.*

["Edan Shavit" <Edan.S@puresight.com>]

Hi All,
We have been using OpenLDAP 2.0.* on Linux for some time now. Recently
we decided to move to the new OpenLDAP 2.1.*. 
We experience some difficulties with the configuration we were using in
OpenLDAP 2.0.*. The problems start in the installation process, and the
installation process failed. 

This is the add lines to slapd.conf we ware using up to OpenLDAP 2.0.*:
    include         /etc/openldap/schema/my.schema
    database        ldbm
    threads         1
    suffix          "cn=root"
    readonly off
    rootdn          "cn=Manager,cn=root"
    rootpw          root
    index   objectClass	eq
    index   cn,entryPath,notificationStamp        eq
    directory       	/usr/local/ldap
    updatedn	"cn=Manager,cn=root"

After some trials and a lot of errors, we found out that if we remove
the "threads" directive we can install our product on OpenLDAP 2.1.*.

My Questions are:
1)	Is there a reason for using the "threads" directive in OpenLDAP
2.0.*?
2)	Is there a correct value of the "threads" directive that can be
use for both versions? 
3)	If  there is non, what is the generic way to know the OpenLDAP
when I install my product.