Search Description:

This script will move the SharePoint 2013 Search Index
Run the function with the 3 required Parameters

function Move-SPEnterpriseSearchIndex($SearchServiceName,$Server,$IndexLocation){
Add-PSSnapin Microsoft.SharePoint.PowerShell -ea 0;

#Gets the Search Service Application
$SSA = Get-SPServiceApplication -Name $SearchServiceName;
if (!$?){throw “Cant find a Search Service Application: "$SearchServiceName“”;}
#Gets the Search Service Instance on the Specified Server
$Instance = Get-SPEnterpriseSearchServiceInstance -Identity $Server;
if (!$?){throw “Cant find a Search Service Instance on Server: "$Server“”;}
#Gets the current Search Topology
$Current = Get-SPEnterpriseSearchTopology -SearchApplication $SSA -Active;
if (!$?){throw “There is no Active Topology, you can try removing the "-Active” from the line above in the script”;}
#Creates a Copy of the current Search Topology
$Clone = New-SPEnterpriseSearchTopology -Clone -SearchApplication $SSA -SearchTopology $Current;
#Adds a new Index Component with the new Index Location
New-SPEnterpriseSearchIndexComponent -SearchTopology $Clone -IndexPartition 0 -SearchServiceInstance $Instance -RootDirectory $IndexLocation | Out-Null;
if (!$?){throw “Make sure that Index Location "$IndexLocation” exists on Server: "$Server“”;}
#Sets our new Search Topology as Active
Set-SPEnterpriseSearchTopology -Identity $Clone;
#Removes the old Search Topology
Remove-SPEnterpriseSearchTopology -Identity $Current -Confirm:$false;
#Now we need to remove the extra Index Component
#Gets the Search Topology
$Current = Get-SPEnterpriseSearchTopology -SearchApplication $SSA -Active;
#Creates a copy of the current Search Topology
$Clone=New-SPEnterpriseSearchTopology -Clone -SearchApplication $SSA -SearchTopology $Current;
#Removes the old Index Component from the Search Topology
Get-SPEnterpriseSearchComponent -SearchTopology $Clone | ? {($.GetType().Name -eq “IndexComponent”) -and ($.ServerName -eq $($Instance.Server.Address)) -and ($_.RootDirectory -ne $IndexLocation)} | Remove-SPEnterpriseSearchComponent -SearchTopology $Clone -Confirm:$false;
#Sets our new Search Topology as Active
Set-SPEnterpriseSearchTopology -Identity $Clone;
#Removes the old Search Topology
Remove-SPEnterpriseSearchTopology -Identity $Current -Confirm:$False;
Write-Host “The Index has been moved to $IndexLocation on $Server”
Write-Host “This will not remove the data from the old index location. You will have to do that manually :)”
}
Move-SPEnterpriseSearchIndex -SearchServiceName “Search Service Application” -Server “SP2013-WFE” -IndexLocation “C:Index”

SharePoint 2013 places the Search index in the C: by default. There are many reasons why you would want to move the index to a different places.
This script will take three parameters, the Search Service Name, the Server Name and Index Location.  There is an example on the bottom of the script.