Summary
If a license server contains license files whose Subscription Advantage dates have expired as well as license files that have valid Subscription Advantage dates, the Citrix License Server may not allow connections to the newer versions of Citrix Products such as Presentation Server. This issue may occur if user licenses were checked out from the license server with an expired Subscription Advantage date. The user may not be able to log into the newer Product until previous connections to the older Product are released, despite the appearance of having enough licenses in the pool.
Background
All Citrix Products require valid Product Specific license files on the license server. Current Subscription Advantage licenses allow Citrix products, such as Presentation Server, to grant access to client connections across multiple versions. For more information on the date based requirements of licensing, See CTX103625 – Future Access Suite Products May Not Function Depending on the Date in the License File.
Figure 1 describes a scenario for Presentation Server products:
A valid Subscription Advantage date in a license file allows connections to current and older versions of Citrix products. An expired Subscription Advantage date in a license file can prevent connections to newer versions of Citrix products. To avoid this issue, a customer merely needs to remain current with Subscription Advantage rather than purchasing additional licenses in order to fulfill all client connection requests.
Using Presentation Server as the example, Figure 1 above illustrates a company with a total of two Presentation Server 3.0 equivalent licenses and two Presentation Server 4.0 equivalent licenses. The users can make connections to both the Presentation Server 3.0 servers and the Presentation Server 4.0 servers using all four licenses as long as the Subscription Advantage dates in the license files remain current. However, if the Presentation Server 3.0 equivalent licenses with Subscription Advantage expire, the users that established connections (for example, U2 in Figure 2) using those licenses will not be able to connect to a Presentation Server 4.0 server. Also, despite the appearance of having enough connection licenses, once the number of connections allowed by the newer licenses is exhausted, no further connections can be made to the newer version of the product as illustrated by U5’s failed connection attempt in Figure 2 below.
Only users that acquire the newer Presentation Server 4.0 equivalent licenses with valid Subscription Advantage dates (highlighted in Figure 2 in blue) will be able to connect to the Presentation Server 4.0 server. Unless Subscription Advantage is updated, the lapsed Presentation Server 3.0 equivalent licenses cannot be used for Presentation Server 4.0 connections.
Potential Concerns
One scenario where this issue could create a problem is if a customer has two license files on the License server and has allowed one to lapse. For example, the first has a valid Subscription Advantage date and the second has an expired Subscription Advantage Date. Both license files could have a 20 user count for Presentation Server Enterprise Edition and the License Management Console would display a total of 40 licenses available. Although concurrent connections are fewer than the maximum capacity available, connection attempts to the Presentation Server 4.0 servers would fail if made using the expired licenses, while connections to the Presentation Server 3.0 servers would be successful using either license. This issue of refused connections to the Presentation Server 4.0 servers despite the appearance of enough licenses can be further exacerbated by the allotment of current Subscription Advantage Presentation Server 4.0 equivalent licenses for connections made to the Presentation Server3.0 server. An environment of disparate licenses would be difficult to manage and could result in perceived random denials of connections. Remaining current with Subscription Advantage eliminates issues similar to the one described here.
The issues described in this article are not limited to mixed version farms; separate farms pointing to the same license server and thus receiving licenses from the same pool of licenses can see these issues.
Recommendations
1. Ensure that you have the maximum number of licenses that users will consume to avoid usage blocks.
2. Get current on Subscription Advantage. If Subscription Advantage is current, license consumption is not an issue, assuming there are enough licenses in the system, or if the customer upgrades older licenses (e.g. Presentation Server 3.0 licenses to 4.0) this limitation is eliminated.
3. To ensure that the appropriate licenses are checked out for each version and thus circumventing the issue, install two Citrix License Servers and separate the license files with valid and expired Subscription Advantage dates. Assign each Presentation Server to the appropriate License Server.
4. Purchase additional licenses with valid Subscription Advantage dates that can be used by all versions of the Product. For example, a license file with a Subscription Expiration date of 2006.0131 can be used for Presentation Server 3.0 and Presentation Server 4.0.
5. Consider reserving Presentation Server 4.0 licenses specifically for the Presentation Server 4.0 servers which will limit the Presentation Server 3.0 servers from consuming Presentation Server 4.0 licenses by using the RESERVE command in the options file. Please note it is necessary to add VERSION=”the SA date” next to the RESERVE option, for example:
RESERVE 10 MPS_ENT_CCU:VERSION=2006.0210 HOST_GROUP TestGroup
Where the HOST_GROUP identified as TestGroup is defined in the options file and 2006.0210 is the Subscription Advantage expiration date found in the license file. New licenses can be purchased if the number of users increases in the older Farm.
For further information about using RESERVE in the license options file, see CTX106282 –Citrix Access Suite Licensing Guide.
