Search Service configuration to Single server under (2 WFE+1 SQL+1Search)

Run the below commands to SP 2016 Search server


$App1 = "MCMYPSPA01"

$SearchAppPoolName = "SharePoint Search Application pool"
$SearchAppPoolAccountName = "apps\svc.srch"
$SearchServiceName = "SharePoint Search Service Application"
$SearchServiceProxyName = "SharePoint Search Proxy"
$DatabaseName = "SP_Prod_AppFarmA_Search_AdminDB"
 
#Create a Search Service Application Pool
$spAppPool = New-SPServiceApplicationPool -Name $SearchAppPoolName -Account $SearchAppPoolAccountName -Verbose

#Start Search Service Instance on all Application Servers
Start-SPEnterpriseSearchServiceInstance $App1 -ErrorAction SilentlyContinue
#Start-SPEnterpriseSearchServiceInstance $App2 -ErrorAction SilentlyContinue
Start-SPEnterpriseSearchQueryAndSiteSettingsServiceInstance $App1 -ErrorAction SilentlyContinue
#Start-SPEnterpriseSearchQueryAndSiteSettingsServiceInstance $App2 -ErrorAction SilentlyContinue

#Create Search Service Application
$ServiceApplication = New-SPEnterpriseSearchServiceApplication -Partitioned -Name $SearchServiceName -ApplicationPool $spAppPool.Name -DatabaseName $DatabaseName

#Create Search Service Proxy
New-SPEnterpriseSearchServiceApplicationProxy -Partitioned -Name $SearchServiceProxyName -SearchApplication $ServiceApplication

#----------------------------------------------------

$clone = $ServiceApplication.ActiveTopology.Clone()
$App1SSI = Get-SPEnterpriseSearchServiceInstance -Identity $App1

#We need only one admin component
New-SPEnterpriseSearchAdminComponent –SearchTopology $clone -SearchServiceInstance $App1SSI

#We need content processing components
New-SPEnterpriseSearchContentProcessingComponent –SearchTopology $clone -SearchServiceInstance $App1SSI


#We need analytics processing components
New-SPEnterpriseSearchAnalyticsProcessingComponent –SearchTopology $clone -SearchServiceInstance $App1SSI


#We need crawl components
New-SPEnterpriseSearchCrawlComponent –SearchTopology $clone -SearchServiceInstance $App1SSI


#We need query processing components
New-SPEnterpriseSearchQueryProcessingComponent –SearchTopology $clone -SearchServiceInstance $App1SSI


#---------------------------------------------------------

#Set the primary and replica index location; ensure these drives and folders exist on application servers
$PrimaryIndexLocation = "E:\SharePoint\index\Data"

#We need index partitions and replicas for each partition. Follow the sequence.
New-SPEnterpriseSearchIndexComponent –SearchTopology $clone -SearchServiceInstance $App1SSI -RootDirectory $PrimaryIndexLocation -IndexPartition 0
$clone.Activate()