Much of the consolidation is driven by "accountants" who try to do the whole thing with SAN's and servers. Lots of stats about cpu unused, disks unused, so you get all your arrays as raid 5 carved into logical disks so that there's no "wasted" space.  fill up the disks, fill up the cpu's fill up the servers, one server with lots of instances, or virtual servers sharing resource of having resource shared and restricted.

I have some sympathies, having had to endure 3rd party apps ( who are probably the worst offenders ) who make statements like " it has to be a dedicated server otherwise we won't support you"  oh and all the users have to be dbo or sysadmin - so you wouldn't want to consolidate anyway!

It sort of makes some sense with 64bit especially but at the end of the day much of the consolidation is about providing hardware which is often vendor only supported - have you ever tried convincing anyone that a SAN is a performance bottleneck ? - there's lots of good things for them ( the vendors ) but maybe not for the dba.  200 databases still need managing regardless of them being on 5 or 50 servers -

My experience is that often consolidation actually degrades performance, especially as the DBA's aren't normally consulted anyway and the "consultants" often know nothing about rdbms let alone sql server.

Hi Steve Jones,

Great article , I really enjoyed reading it. I like your business saving ideas on consolidation of servers

thanks

sri

An option that needs to be explored is using VMs such as either MS Virtual Server or VMWare.  This would go a long way towards ameliorating the concerns in the article with regards to patches required for one app conflicting with another.  Other miscellaney software issues that can crop up only affect one VM at a time.  VMWare long ago passed the point where it just runs along smoothly without problems in itself so as long as the host server is of sufficient enterprise quality and isn't pulling other duty.  The host system's downtime is a very rare occurance.  I've used multiple SQL servers on VMs within a well equipped, quality host server and it works quite well as long as the time is taken to properly allocate the resources for the individual VMs via the host VM management.  Overselling the CPUs for example (such as 8 VMs each allowed to use 2 CPUs each in an 8 way) functions well under light loads but leads to performance issues when all are used heavily enough that the VMs fight for time on the real CPUs.  But the same server with only 4 VMs allowed to use 2 CPUs each could run at reasonably high loads.  The same applies to disks, RAM, etc, etc, but you get the idea.

The problem with this idea is that it eliminates the cost savings in software licensing for the OS and SQL Server as each VM needs its own license.  But in hardware the savings are still considerable.  Also, such licenses as backup software are still able to be consolidated.  You only need one backup license to be run on the host OS.  Its also easier to manage only one host physical server sitting in the rack even though there is still the same level of software management of the individual servers within the VMs.

Anyway, just my 2 cents on the consolidation issue.  Your mileage may vary.