ClearCase License Mechanism with FAQ

originally compiled by Yossi Sidi on CCIUG

[see other ClearCasePages on this CMWiki]

-- DavidBaird? - 07 Jan 2004

1.1 Introduction

The best one-line description of how ClearCase licensing works is that it is a "floating concurrent user licensing method". When you want to use ClearCase, a license is obtained automatically. As you continue to use the product, you retain your license. When you are not using ClearCase, your license times out after a default idle period of 60 minutes (configurable). At that time, the license is returned to the pool for other users to use.

The licensing mechanism described here applies to full ClearCase. ClearCase LT uses FlexLM which behaves differently. -- FrankSchophuizen? - 08 Jan 2004

1.2 Accessing ClearCase

The first question that new users have is what constitutes "accessing" ClearCase. The answer is, most anything you do that involves the product will consume a license. Anytime you are in a VOB, looking at data through a view, you take a license, whether you are on a ClearCase host or a non-supported host via an exported view. This is in addition to any cleartool commands that modify data (checkout, checkin, etc.). Any metadata operations on labels, branches, attributes, triggers etc. will consume a license as well. Also any listing or reporting commands like lsvob, lsview, describe, find, etc. take a license as well. So does Clearmake and merge. The general rule of thumb is that any ClearCase operation that involves the database (MVFS access) or the albd_server will most likely cause a license to be activated for that user.

The above applies to dynamic views. Snapshot views, when disconnected from ClearCase, do not use a license. But snapshot views connected to ClearCase do use a license for ClearCase operations like update, checkout, checkin, etc. -- FrankSchophuizen? - 08 Jan 2004

1.3 Defining a User in ClearCase

Another common question is what constitutes a user. For ClearCase, your logon userid is how ClearCase identifies you. Unlike other licensing tools, clearlicense does not hard-code users to licenses. That makes it nice when new developers start on a ClearCase project, or when employees leave a project. The ClearCase license floats across all UNIX and NT platforms, which is also very convenient for cross-platform development too. A user 'Zvika' logged in on several machines in several different views using ClearCase concurrently takes at most one license. Large sites should make sure their userid/group id mappings are consistent across all machines so that ClearCase does not assign two licenses to the same effective user. When a user stops using ClearCase, their license will expire after an idle period (typically 60 minutes, in CORRIGENT 30 minutes) and "float" back to the available pool of licenses, so ClearCase licenses are not hard-coded to a userid.

1.4 Determining a License Server Host

For most sites that have all of their VOB repositories on a dedicated server, it makes sense to have that machine act as license server as well as the registry server for point-of-failure reasons. If a site has VOBs spread out on more than on server, then you want to either make sure your license server host is the most reliable and accessible machine in your network, or make more than one machine a license server by splitting licenses up.

1.5. Clearlicense Internal Details

Here is what happens:

• Remember, there are three "programs" involved:
  1. the client tool (cleartool, clearmake, xcleardiff, ...)
  2. the view server for your view
  3. the "license server" on some host somewhere.
• When you run a client tool, or access a view via the MVFS (e.g. cat/type/read/open a file) a license check is initiated (by the client tool or the view server).
• If a successful license check has been made by the same user from the same machine within 15 minutes the check is skipped and the command proceeds -- this "local license cache" is a performance optimization that helps reduce the load on the license server. This also explains why simple "experiments" to see what the licensing mechanism does do not show you what you might expect.
• After 15 minutes are up a real check against the license server is made and the 15 minute local cache is reset to 15 minutes.
• When the license server receives your license check request it will reset the "license timer" to one 30 minutes (in CORRIGENT).
• If you don't check your license within 30 minutes, you lose it, but you will silently get it back when you perform a ClearCase/MVFS operation (unless you are totally out of licenses).
• A long running GMAKE should refresh the license when you do MVFS accesses (on dynamic views).

The client workstation uses a port above 1024 (1129, say) and talks to the license server's albd on port 371. They exchange about 12 packets of various sizes, each less than a few hundred bytes. If you are sharing a license pool across a complicated LAN or WAN, be sure to prioritize this traffic on your lowest latency route in order to get best response. -- AlanZimmerman? - 17 Jun 2005

1.6 Clearlicense Features

Features you can add to the license file include adjusting the timeout period, specifying user priorities, excluding users, and enabling license auditing.

1.7 Questions

• 1.7.1 If I am logged in to two different machines accessing ClearCase, how many licenses am I using?
  One.

• 1.7.2 If I am logged into a NT machine and a UNIX machine doing ClearCase work as the same user, how many licenses am I using?
  One.

• 1.7.3 If I am in more than one view as the same user, how many ClearCase licenses am I using?
  One.

• 1.7.4 If I am in a view but doing no checkouts/checkins, am I taking up a license?
  Yes, if you are in a dynamic view. No, if you are in a snapshot view.

• 1.7.5 What if I am just logged in as a manager or a QA person who is doing no development?
  You still take one license.

• 1.7.6 What about exported views being accessed by non-ClearCase machines? Will those remote accesses take up a license?
  Yes. Technically, anything that access the database will consume a license, which is most of the ClearCase commands as well as viewing data under ClearCase control.

• 1.7.7 What is the lowest timeout period I can set for ClearCase licenses?
  30 minutes.

• 1.7.8 How many licenses do we need?
  Consult your local Sales team to size how many licenses you will need. Generally, smaller groups will need about a 1-to-1 ratio of licenses to users, while larger groups will tend not to need a 1-to-1 ratio of licenses. The ratio is highly dependent on a number of factors, such as how often a user accesses ClearCase during the day, how many meetings users attend, days out due to vacation, sick leave, family leave, etc. For a group of 50 developers, an 80% ratio of licenses to users would be a sufficient estimate given that not every developer is in ClearCase nonstop all day. Always be on the safe side when estimating license usage, and anticipate future growth over the next 6-12 months.