Applying new SharePoint Enterprise Search Query Topology fails with Crawl Component cannot be dismounted

Question

I am trying to scale out our search topology by adding a new Index Partition and Query Servers. The approach that is being taken is using PowerShell to build a new SharePoint Search Query Topology using New-SPEnterpriseSearchQueryTopology.

This topology has two index partitions which in turn have two query components that are pointing to the same property database.

When the topology is applied with Set-SPEnterpriseSearchQueryTopology the powershell command processes for about 12 minutes but fails with the following error:- ActivationError: Crawl Component 'GUID-crawl-0' on [ServerName] cannot be dismounted. Check that the server is available.

Looking at the ULS logs on the server we see that the 'Application Server Administration Job' failed for service instance Microsoft.Office.Server.Search.Administration.ServerServiceInstance. Reason: The Remote Procedure call failed. Exception 0x800706BE).

Prior to that we have an error from mssearch.exe which is location d:\office\source\search\libs\util\hangrecoverer.cxx161) condition !"Application dismount hangs".

It seems that the dismount is failing and timing out and that causes the topology changes to fail to be applied.

Has anyone had experiences like this?

Answer 1

The issue seemed to be down to the size of the Index Partition. We reduced the number of items in the index using crawl rules and were able to get it down to about 8 million items from 12 million.

We were able to then make changes to the search topology.

What was interesting was the SharePoint Search Service on the rogue Crawl server would take about 90 seconds to restart. Once the index was reduced down it took about 5-10 seconds.

I guess this is one of the reasons why the supported maximum number of items in an index partition is 10 million items.

Answer 2

Run the configuration wizard once again, I assume your DB layout is not in sync.