For some reason indexing automatically has stopped working in my Fast Environment. I have to manually issue a indexeradmin resetindex command for the index to update. Is there anything I can do to prevent this behavior?

1) Clear-FastSearchContentCollection requires a indexeradmin resetindex for the changes to be applied.

2) Crawling any new content also requires indexeradmin resetindex for any items to become searchable. 

Here is an example of what I see with indexerinfo. I have two indexers and they seem to be out of sync number of documents does not match.

<?xml version="1.0"?>
<indexer hostname="FASTIDX.my.lab" port="13050" cluster="webcluster" column="0" row="0" factory_type="filehash" preferred_master="no" connected_feeds="1" status="running ok" heartbeat="Running" exclusion_interval="60" time_since_last_index="122">
  <documents size="17677625600.000000" total="249325" indexed="85615" not_indexed="163710"/>
  <column_role state="Master" backups="1"/>
  <index_frequence min="295.000000" max="882.680420"/>
  <partition id="0" index_id="1372693387216690000" status="copying (100%)" type="dynamic" timestamp_indexed="1372693392" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="1" index_id="1372693382950835000" status="idle" type="dynamic" timestamp_indexed="1372693387" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="2" index_id="1372693378794346000" status="idle" type="dynamic" timestamp_indexed="1372693382" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="3" index_id="1372693372325223000" status="idle" type="dynamic" timestamp_indexed="1372693378" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="4" index_id="1372693272910617000" status="idle" type="dynamic" timestamp_indexed="1372693372" indexed_per_second="755.262939" pending_exclusionlist="0" range="19983-85571">
    <documents active="85615" total="85615"/>
  </partition>
  <document_api number_of_elements="0" last_sequence="7410786" frequence="1.166667" load="0.000000" status_updates="0">
    <queue_size current="0"/>
    <operations_processed api="172686"/>
  </document_api>
</indexer>

<?xml version="1.0"?>
<indexer hostname="FASTQRY.my.lab" port="13050" cluster="webcluster" column="0" row="1" factory_type="filehash" preferred_master="no" status="running ok" heartbeat="Running" exclusion_interval="60" time_since_last_index="0">
  <documents size="49003614139.000000" total="916126" indexed="85615" not_indexed="830511"/>
  <column_role state="Backup" backups="0"/>
  <index_frequence min="0.000000" max="0.000000"/>
  <partition id="0" index_id="1372693173174499000" status="idle" type="dynamic" timestamp_indexed="1372693177" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="1" index_id="1372693168799387000" status="idle" type="dynamic" timestamp_indexed="1372693173" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="2" index_id="1372693163705507000" status="idle" type="dynamic" timestamp_indexed="1372693168" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="3" index_id="1372693155752261000" status="idle" type="dynamic" timestamp_indexed="1372693163" indexed_per_second="0.000000" pending_exclusionlist="0" range="0-0">
    <documents active="0" total="0"/>
  </partition>
  <partition id="4" index_id="1372693054031342000" status="idle" type="dynamic" timestamp_indexed="1372693155" indexed_per_second="0.000000" pending_exclusionlist="0" range="19983-85571">
    <documents active="85615" total="85615"/>
  </partition>
  <document_api number_of_elements="0" last_sequence="6192829" frequence="0.000000" load="0.000000" status_updates="0">
    <queue_size current="0"/>
    <operations_processed api="0"/>
  </document_api>
</indexer>

Found my answer by performance steps 1-3

http://support. microsoft.com/kb/2017823

Glad you found a solution. Index status from the indexerinfo looks ok.
If indexer get out of sync again, you can manually sync them using the steps illustrated in the below article.
http://technet.microsoft.com/en-us/library/gg482028.aspx