Missing Indexes after Restart

We have decided to use ApacheDS (version 2.0.0.AM25) for Authentication in our product. Ldap Server and Directory Service are being used in Embedded Mode.

During our Tests we found that after Restart, some of the Entries via Indexed Attribute Search Filter are not comming in search result. After considering various possibilities we found that it is Indexing problem. We used Repair commnd and then we see those entries in search results.

Why some of the indexes were missing even it was a gracefull shutdown?

We want to avoid repair command after every restart unless it is really necessary. Our product will serve in future more than 50K users, we have fear that it would cost us a lot if we encounter those unexpected problems.  

These are two attributes used in our search filters

dn: ads-indexAttributeId=mail,ou=indexes,ads-partitionId=tsi,ou=part
itions,ads-directoryServiceId=default,ou=config
ads-indexattributeid: mail
ads-indexHasReverse: FALSE
ads-indexcachesize: 1000
objectclass: ads-index
objectclass: ads-jdbmIndex
objectclass: ads-base
objectclass: top
ads-enabled: TRUE

dn: ads-indexAttributeId=telID,ou=indexes,ads-partitionId=tsi,ou=part
itions,ads-directoryServiceId=default,ou=config
ads-indexattributeid: telID
ads-indexHasReverse: FALSE
ads-indexcachesize: 1000
objectclass: ads-index
objectclass: ads-jdbmIndex
objectclass: ads-base
objectclass: top
ads-enabled: TRUE