We are managing large SharePoint search application with 15 Million items in Indexer .

Search service is hosted in two servers with server1 as primary index component and server2 as replica.

We added 500 GB disk space to both servers initially and with the growing indexing items, the available free disk space is 150 GB.

Will index still continue till the 150 GB space consumed or the search service needs minimum free disk space?

How much minimum free space we should keep to run the index component without any disruption.


The recommendation is 30% of the size of your corpus (the "stuff that you are indexing") free on the disk serving the index. At any time, you will only see a disk allocation of 10-15%, but the 30% number accounts for dynamically allocating space for the index and performing routine master merges.

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  • currently i have 30% free space left on index drive and getting the error message about the master merge is halted like below. A master merge has been halted for catalog ms\%default due to low disk space. As a result query latency will be adversely affected. Free some disk space on the disk drive hosting the catalog to allow the next master merge to complete... Will the indexing be continued till i have some 10% free space on indexing drive? – kumar Jun 26 '18 at 13:23
  • It's not 30% of the disk space. It's 30% of what you are indexing (the corpus). If you are indexing 1TB of content the recommendation is that you have 1TB*0.3 = 300GB disk space for your index. – Matthew McDermott Jun 26 '18 at 17:32
  • Great, can I get an answer vote? – Matthew McDermott Jun 29 '18 at 14:01

SharePoint Search will consume all available disk space until the volume is running out of disk space. So keep an eye on this volume as it will lead to issues with the index such as:

  • new items will not be added to search index
  • search will be slowed down
  • search maybe will stop working

I do not remember any best practice minimum free disk space for index partitions. I would suggest having 25 GB of minimum free disk space to avoid being surprised by running out of space when more items are added to SharePoint.

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  • As I remember, it must be bigger than volume of all Content DB. + Turn off antivirus (it may block crawl files deleting) or exclude control of C:\Program Files\Microsoft Office Servers\15.0\Data folder – AlexZh Jun 25 '18 at 11:56

We have built a number of SharePoint Search Farms. General practice is to allocate 3x space per partition. This is a bit overkill however, Master Merge behaves much better. We have about 14 million items. We allocate 1.4 TB per Partition and two Partition Servers. This is federated search across 6 data sources. Thanks/Good Searching.

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