February 2, 2005 at 7:43 am
Hello guys,
I'm very close to build a sql cluster.I propose a solution with a/passive, with W2003AD,2 sql A/P and IIS Application level separated .
My manager want to implement a solution with Active Directory installed on the same SQl server nodes.It's a good practice ?Why not?
Thanks,
Stan Gabriel
February 3, 2005 at 7:55 am
My opinion as a Full-time coder, Part time server and DB administrator:
It depends on the size and nature of your business and what types of applications you'll be needing the clusters for. Just the fact that you are considering the need for the redundancy and scalability ot a cluster leads me to say No. You should avoid over-utilizing your cluster.
A couple of reasons:
1.) You don't want to over-allocate your hardware. Even though you will have a cluster of two or more servers, in an Active-Passive setup, only one of them will be active at any given time. This puts the processing burdon for all tasks firmly on the back of one server. You are, essentially running everything off of one machine. If you would normally run AD, SQL Server, etc... off of one machine then go for it. I wouldn't, though, if I had the choice.
2.) You don't want to over-allocate your hardware. SQL Server and Active Directory can both produce a good bit of network traffic (especially AD during replication) and I don't know that I would be comfortable merging both of these mission critical services in to one (or several) LAN card(s) on one A/P array hung off the same switch. You are combining way too many points of failurs thereby increasing the risk of downtime.
3.) You don't want to over-allocate your hardware. It will make connectivity and performance issues much more difficult to diagnose and remedy. Is the performance issue with Active Directory or SQL Server or a web app or something else entirely?!?
FYI: We Have two A/P web clusters communicating with two backend SQL2000 Db clusters and AD2003 on completely separate machines on different switches and the arrangement works great.
February 3, 2005 at 8:08 am
I would also worry about security and "putting all your eggs in one basket."
If you get hit by a SQL Server worm, you've also taken down your domain authentication services. If you have to apply a security patch to fix a AD issue, you may mess up a SQL Server application (or vice versa).
One of my instructors had a term for this idea - Creeping Elegance. You've got one box (or cluster in this case) that does it all. It just doesn't do anything particularly well.
February 3, 2005 at 2:00 pm
To minumize hardware 'waste' due to clustering we do the following:
Primary node --> HP DL-580, Quad CPU, 4 Gb RAM
Secondary node --> HP DL-380, Dual CPU, 4 Gb RAM
The thought process is that if we fail over it is a short term (less than 4 hours) issue. Life goes on, just a little slower.
As for the initial question ...
AD on it's own box - not a cluster, there should be another AD box as well well.
SQL on its own box - preferably a cluster, although standalone is OK based on your SLA.
IIS on its own box - preferably a cluster, although standalone is OK based on your SLA.
We presently have SQL Server on one of our 4 old core DC's (we're almost 95% into AD now). This lone server has out Helpdesk software and DB on it and has caused dozens of outage issues for SQL (due to AD type issues) and a number of AD isssues due to SQL maintenance and applicaton software maintenance (not my call, it was inherited).
My advice, beg borrow or steal to keep these things separate. It's cost me about 1 day and 2 nights a month for the last 8 months. I cannot wait to migrate the database to one of our clusters.
RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."
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