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Re: cvs vs. clearcase?

From: Paul Sander
Subject: Re: cvs vs. clearcase?
Date: Mon, 29 Nov 2004 23:10:43 -0800

On Nov 29, 2004, at 8:53 AM, address@hidden wrote:

Hash: SHA1

Mike <address@hidden> writes:

I have a director asking why I don't want to user the company's
clear case server. One item I mentioned is the lack of integration
into unix tools and the lack of a unix client. Are these good/valid
reasons? What are other reasons?

    - Cost per seat of support of Clearcase can be high

For 50 seats, the price of initial licensing is about $4k/seat, then $400/yr thereafter. After the first year, its cost is in the noise floor.

    - Cost of View servers and Vob servers can be high

But not significantly higher than the cost of the file servers you'd need to buy otherwise. Also, ClearCase offers enough opportunities for disk space sharing that you will likely need fewer of them. On the other hand, your network must be rock solid, and it must be fast; this may be an issue for some shops. If you're worried about this, consider using ClearCase snapshot views, which are more like CVS workspaces.

    - Technical training/expertise of the support staff favors CVS,
      so you need to train or hire Clearcase administrators.

This is true.

    - Many people do not trust the security of running a system that
      needs to modify the operational integrity of the kernel on both
      their clients and servers in order to operate effectively with

The drivers supplied with ClearCase undergo a commercial grade quality assurance program, and their reliability is comparable to the kernel. The application itself also undergoes a commercial grade quality assurance program, a claim that CVS cannot make.

    - Clearcase is a primarily US-based SCM system while CVS is used
      by a large part of the international community.

Depends on where you draw the bar that qualifies "primarily". Last I heard, 30%-40% of ClearCase revenue comes from outside the USA. It's used heavily in India, Israel, and the Arab world.

    - If you already have a highly integrated environment using CVS,
      you should be able to write a technical paper on the cost of
      the transition from CVS to Clearcase for your particular area.

I was able to convert a CVS-based shop to ClearCase, including some 400k lines of code in a week, and supplied daily conversions while the development groups switched over.

    - Technical training/expertise of the support staff favors CVS,
      so you need to train or hire Clearcase administrators.

This is true.

    - Adding additional features to CVS is possible as you have the
      source, forcing IBM to change anything for you is not as easy.

On the other hand, some believe that ClearCase does everything already. :-) It certainly supplies most of the features requested in this forum to be implemented in CVS. Also keep in mind that such claims as the above are only theoretical; source code doesn't make up for bad design, and I have personally have been unable to implement certain capabilities well with CVS because its architecture simply wasn't compatible with the problem I needed to solve.

    - The future of Open Source development looks bright and you wish
      to attract Open Source community into joint development with one
      or more of your projects.

Many companies don't care about this...

    - Your developers will quit if they are forced to use Clearcase.

In practice I doubt this is true. I know of two cases where the developers would have been ecstatic to use anything other than CVS. Ask around before making this claim.

    - Your developers will require many hours or re-education if they
      are forced to transition to a new SCM system and they do not
      like change.

I had developers productive with ClearCase after a 1-hour lecture and 30 minutes' practice. The learning curve for the everyday stuff is pretty low. The learning curve for ClearCase in total is high, but most users don't need to access its complete functionality.

your company able to get an agreement to escrow the source code for
ClearCase should the vendor (IBM now owns Rational which purchased Pure
which purchased Atria that originally wrote ClearCase) choose not to
continue to provide the product at some future date?

There's little need for this. Once you have purchased ClearCase licenses, they don't expire. So as long as you have compatible hardware and OS, you can access ClearCase. If maintenance stops for whatever reason (by the customer's choosing or not) then it's relatively easy to pluck out the data and metadata to convert to something else.

If you have a large invested use of 'cvs' in your shop, then transition
to clear case could be expensive. Certainly there are different
administration problems with the extra hardware needed for View and Vob
servers and the cost of doing distributed development using MultiSite
can be high in terms of dollars and man-hours of effort.

MultiSite does double the license and maintenance cost of ClearCase. See above for my take on the "extra hardware" issue.

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