I can certainly see the merit in your approach.  It also tends to
reduce the dependancy on a single point of failure.

However, what would worry me is the Capital & Operating cost of this
approach.  The costs will increase proportionally as the number of
servers increases.  In our environment (using AIX) we are finding it
quite easy to scale up to manage increasing volumes of data, using a
single server, without significantly increasing the cost.  In fact the
bigger we are getting the cost per MB of data being backed up/stored is
reducing which is quite helpful in attracting customers and
centralising all our backups in the organisation.  This in turn is
reducing the overall cost to the company of providing a Storage
Management service.

The other advantage of a larger server is that it can be designed to
make more effective use of resources than can many separate servers.
Much like a four lane highway can carry a lot more traffic than 4
single lane roads.  Restore performance can also be significantly
improved as a single restore can make use of the resources of the
complete large system (depending on design of pools etc.), rather than
only getting the resources of one of a number of smaller systems.

In our case AIX is a clear winner over NT, simply because it is more
scallable & offers better performance, and in fact the Total Cost of
providing the solution is cheaper than it would be with NT.  Of course
if a single NT server offers sufficient performance then it is a very
good choice.

Regards,
Simon
----------
| From: c.jordan /  mime, , , c.jordan AT ELSEVIER.CO DOT UK
| From: c.jordan /  mime, , , c.jordan AT ELSEVIER.CO DOT UK
| To: ADSM-L /  mime, , , ADSM-L AT VM.MARIST DOT EDU
| Subject: Re: ADSM Bottleneck
| Date: Friday, 20 August, 1999 5:47PM
|
| We used the building block approach. Designing a "balanced" (we hope!)
| system of a certain size. Each of these blocks can back up about 20 to 30
| clients with a total disk usage of about 2 TBytes (we hope!). When we have
| more clients to back up, then we add another building block - which includes
| a new NT server, memory, disk cache, tape library etc.....
| This spreads the load, requires less ADSM tuning knowledge, and allows easy
| to understand expansion in the future.
|
| Cheers, Chris
|
| -----Original Message-----
| From: Rodrigo Cordovil Gazzaneo [mailto:rgazzaneo AT INFOLINK.COM DOT BR]
| Sent: 20 August 1999 03:50
| To: ADSM-L AT VM.MARIST DOT EDU
| Subject: Re: ADSM Bottleneck
|
|
| NT is your bottleneck !
|
| Sorry for the strong way of saying, but scalability is not the strong point
| for NT, so adding processors is not closer to linear (ideal) performance
| growth.
|
| I am not sure, but NT licensing for SMP systems and the NT system itself
| may not be worth the performance gain.
|
| If I were you I would add memory and try to distribute I/O through many
| disk/tapes controllers. Probably results will be a lot better than just
| adding another CPU.
|
| good luck,
|
| Rodrigo
|
| >We are about to spec out a new ADSM server running NT on the Intel platfor
| >We are interested in opinions of what are the main bottlenecks for ADSM
| >performance. For instance, would adding multiple processors increase
| >performance (especially ADSM DB) or is memory more important. Thanks in
| >advance.
| >Seth Forgosh
|