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Help !! Clustered Servers

By leehellcat ·
Does anyone know anything about clustered servers ?
My company is having an Intranet/Extranet developed that will be have the user interface hanging off our website, and the Database sat on a clustered server in our office. Where do I start with a clustered server. I have been told it will cost around ?20,000($30,000) does this sound right. 2 servers and a 36Gb raid drive doesn't seem a lot of metal for the money?
Also does anyone know hoe reliable these things are, as I am having nightmares about it already and it isn't going to be in until may 2002. So I guess I need to get it sorted soon.

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Clustered Servers

by Zara_29 In reply to Help !! Clustered Servers

Hallo le Cat,

I think that sounds like a lot of dough for that kind of metal, we had to install a simliar solution in our office and I don't belive it cost so much. I could perhaps ask our specialist for details. Regarding servers, there is a lotof info available at the CeBIT, and there you could certainly find some experts, also electronically. Try HP's site on the fair:
I'd look there if I were you. Good luck!

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Ta !

by leehellcat In reply to Clustered Servers

Thanks, I'll have a look. It sounds like a lot of dough, but isn't everything these days in IT ?

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Clustered Servers; if you need them ...

by Jose Mir In reply to Help !! Clustered Servers

Why should an organization need Clustered Servers?
Maybe for supporting a new development!
Maybe for using some extra floor space and extra power in the new UPS!
Maybe ...., maybe ...., maybe ....
If you ask the executive level in the company they should tell you something like : "clust-what?; all I want is the XYZ project running on time, with good performance, and without worring about system failures".
So, if you need to set-up a cluster you better use good hardware, choose the right platform, and give Scalability, High-Availability and Performance it's place in the project goals!
U$D 30000 for a cluster? is too much for a cheap solution (maybe you could have similar MTBF with good hardware and software without going to clustering). But U$D 30000 is nothig in professional systems clustering.
You should first check your needs very carefuly.
Look at IBM ( for info abou clustering, it may be usefull.


Jose P. Mir.-

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by leehellcat In reply to Clustered Servers; if you ...

Thanks, I'll take a look.
I'm not sure about the whole clustered thing, I think that for an organisation with 40 staff it would be better housed off site at a server farm or something !!

I'll take a look at the IBM site and see if I can draw some firm conclusions.

Once again, thanks, I'm kinda in over my head here !

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You are wellcome

by Jose Mir In reply to Cheers

It's a pleasure to help others.

Jose P. Mir

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Help !! Clustered Servers

by aclopez5 In reply to Help !! Clustered Servers

Clustered systems are expensive. $30k does NOT sound like a lot. I would take a good look at the solution and make sure it's not too cheap. Also, 36GB seems awfully small.

The concept of a cluster is simple: 2 servers sharing a single, external RAID enclosure. They also have a dedicated link between the two servers so they can detect if their partner fails. In a Microsoft SQL Cluster, you generally split the RAID between the two servers. Lets say it a 200GB RAID. You create 2 logical drives: G: 100GB and H: 100GB. You assign G: to ServerA and H: to ServerB. Under normal conditions, ServerA will see only the G: drive and ServerB will see only the H: drive. You install 2 instances of SQL on EACH server and name them, for example SQLA and SQLB. SQLA expects to find its data on G: and SQLB expects to find its data on H:. On ServerA, the instance of SQLA will be running and the instance of SQLB will be stopped (these will appear as seperate services). On ServerB, the instance of SQLB will be running and the instance of SQLA will be stopped. Let's assume ServerB fails. ServerA notices immediately that ServerB is not responding. He sends a signal to the RAID enclosure and takes over the H: drive. Now, ServerA has both G: and H:. The cluster software will kick off a process (like a batch file) that will start the SQLB instance running on ServerA which finds its data on H:. The client application is using the SQL instance name to find the data so after a short time-out, the client will reconnect to SQLB not realizing that it is now running on a different server.

As for how reliable they are, that depends on the hardware (don't go cheap) and how well it's configured. Remember, the hardware of EACH server needsto be able to handle the combined load of BOTH servers. Otherwise the server will chock on the load when his partner fails. Under the right circumstances, the results are awesome.

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Okay, heres a bit more info

by leehellcat In reply to Help !! Clustered Servers

Okay. thanks for making the picture a bit clearer. I think I am beginning to get my head around the concept a bit more now.
200GB sounds a lot to me. We only have 30 Users at our site in Cambridge, UK. and we are going to have sattalite sites with2 - 3 users accessing the DB from various sites accross the world via an extranet. Do you really think that 200GB would be neccesary ?
The company is looking to open 2 - 3 sattalite sites a year, and the first is just being opened at the moment in Cambridge, MA.

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by ferocious In reply to Okay, heres a bit more in ...

Hi. Don't get too complacent about what constitutes too much storage space. You should always plan not only to provide a solution for today but for tomorrow, as well. Sure, 200 GB is a lot of space, but your supervisors may decide to take advantage of the new capabilities through other projects, and you want to keep from having to do upgrades that would have been unnecessary if the hard drive space was adequate to start with. Server-based hardware should be as maintenance-free as possible, due to the nature of the service (always online), so the trade-off versus expense is low maintenance, therefore the most reliable (read: more expensive) hardware should be evaluated for implementation. Just an opinion. Have a great day!

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I would agree...

by TTony In reply to Complacency

...with the sentiments expressed in this thread, the key here is to plan for as much re-use as possible. If 200 GB seems over generous then ensure that you identify a solution which allows you to hot plug additional storage as and when required, asthe last thing you want to be doing is asking your management to fund the replacement of the system in 24 months. I think it is also important to assess precisely how much risk the organisation is willing to take and the level of availability they would accept. These answers would then guide you towards a more specific shopping list, which in turn buys you some ownership from the busienss. Good Luck !

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Don’t loose the focus

by Jose Mir In reply to Help !! Clustered Servers

It seems to me that the main question is not about how to partition the disks or launch the processes. Before planning that is necessary to understand the different options and evaluate the needs. Suggesting the size of the hard disks is, at this stage, a wrong indication about the way to follow. Maybe is very clear for experienced people that disk space is never too big, but, this is not relevant to the clustering implementation.
I think the purpose of this Q&A is to give guidelines, not to “teach”. I know the intentions are the best in all of us, but we must keep in mind the fact that our experience and/or knowledge may not be 100% exact, or even if it is, maybe we are not the better communicators. For example, is not true that “Clusters are 2 servers sharing a single, external RAID enclosure”. Clustering is much more than that; and even if I know that this answer could be right in many situations, I must disagree with it because could give the wrong picturein many other situations.
IT is not a self-containing human activity. IT is deeply immerse in a business environment. The solutions that IT implement are implemented to solution some organization’s needs; so it’s necessary analyze theseneeds to find the right solution. With the info we have in this question nobody can give a serious answer; we only can give good information to let “leehellcat” find out the right solution.

Jose P. Mir

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