It’s recommended to elevate the zone election preference on at least two servers in large XenApp farms.  One server’s zone election preference should be set to “most preferred” and the other should be set to ”preferred”.  Most “Citrix people” will refer to those XenApp servers with elevated zone election preferences as the “zone data collectors” or “data collectors”.  The remaining servers in the zone should be set to a lower zone election preference (usually “not preferred”).

More info on IMA and Zone Data Collector Communication

The XenApp Advanced Configuration Tool allows you to change the zone election preference one server at a time. I got tired of torturing myself and figured out how to change the election preference for multiple XenApp servers with Powershell.

Example:

I have a zone with two data collectors.  The data collectors are named XenAppDC01 (most preferrred) and XenAppDC02 (preferred).  I’ve added XenAppDS01 to XenAppDS05 to the farm.  The following Powershell command will move servers that start with “XenAppDS” to “MyZone” and set the election preference to “not preferred”.

Get-XAServer | Where-Object{$_.ServerName.StartsWith("XenAppDS")} | Set-XAServerZone -ZoneName MyZone -ElectionPreference NotPreferred