Incremental search crawl CPU spiking

Question

Our SharePoint WFEs are spiking to 100% CPU when the incremental search crawls start. I have been digging into the issue but nothing seems to stand out. We also have two dedicated search servers configured to run all the search components. I am wondering why the WFEs are even running the crawl since we have dedicated search servers. I have a couple of questions:

1. Can I move the crawling out of the WFEs to these dedicated search servers?
2. Should I set one or both of the search servers as crawl targets?
3. Do I need to enable the Microsoft SharePoint Foundation Web Application service on the search servers in order to switch the target to the search servers? The dedicated search servers are not running the Microsoft SharePoint Foundation Web Application service so the web sites are not in IIS.

The SharePoint search service is not running on the WFEs either. I am wondering if we missed a step when we built the search servers to point the crawl to these servers.

Answer 1

If you follow the streamlined topology or the MinRole topology in SharePoint 2016, all of the Search roles reside on the servers assigned the Search MinRole. There is no issues with moving all of the roles to the Search servers. The FE role does not have any search components.

As far as crawl targets, your target must be running the Foundation Web service and have IIS properly configured (e.g. SSL certificates, Site bindings).

Another thing to consider, and I'm making the assumption your FEs are virtualized, is just adding additional vCPU to it. I would add 2 vCPUs at a time until your CPU usage is under control.