The question here is, is anything acutally still occurring for this index? Do you regularly get event ID 7305 as per the technote below?
http://support.veritas.com/docs/304099
Do you get any errors relating to indexing and this index?
Whenever rebuilding a large index you are better to go back to a good backup of that index and restore, then select update to cut down the wait time.
Depeneding on your EV Version this only covers EV6SP4 could be this
http://support.veritas.com/docs/290008
Could be this?
Index rebuilds appear to stop processing in an environment that utilizes NTFS Collections
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Details:
In an Enterprise Vault (EV) environment that uses NTFS Collections, it is possible that an index rebuild may appear to stop processing due to being unable to extract items from a .cab file.
In this scenario, the Storage Crawler process will appear to loop over the same Digital Vault Saveset (DVS) file, however Windows will notify this process that the file is not yet available.
To Identify this issue:
1. On the Enterprise Vault Server, open a command prompt and begin a DTrace. (See Related Documents article 276120)
2. Enable Dtrace for StorageCrawler
3. In this scenario we would expect to see similar entries repeatedly for the following line:
CItemFetcher::RequestItem (BTID:9308) NextISN:6745942 MaxISN:6923275 Format:3 MaxMarshallSize:10240 (KB) IIRebuildMode:1 (hr=Success [0])
4. If this scenario, the number in the NextISN remains the same repeatedly.
Resolution:
1. In a SQL Query Analyzer, run the following query against the Vault Store that the index or archive belongs to
SELECT C.RelativeFileName AS 'CAB Location', S.CollectionIdentity
FROM Collection C, Saveset S, ArchivePoint AP
WHERE IndexSeqNo = 6745942
AND AP.ArchivePointId = 'ArchiveID'
AND S.ArchivePointIdentity = AP.ArchivePointIdentity
AND S.CollectionIdentity = C.CollectionIdentity
2. Make a note of the path and name of the .cab file.
3. Verify this .cab file exists and the items can be opened.
4. Once verified, contact Enterprise Vault Technical Support for the corresponding version of the UnCollect utility.
5. Identify the partition and .cab file from within the Uncollect utility and extract the items to their original location.
6. Once accomplished, restart the Indexing Service and through a Dtrace of Storage Crawler verify that we are now processing items correctly.
To be honest there is alot it could be. What type of storage and version of EV are you using?
The Indexcheck utility which is covered in the utilities guide will help you minitor the health of the indexes so you can be proactive rather than re-active to issues. May not help you now but in the future ;)