Re: cvs vs. clearcase?

[Paul Sander]

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

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> 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?
>
> Economic:
>     - 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.

> Political:
>     - 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
>       Clearcase.

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.

> Technical:
>     - 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.

> Ideological:
>     - 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...

> Social:
>     - 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.

> Is
> 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.