Redundancy, DFS, and iSCSI

By jnpolizzi ·
Hello all,

Our shop is purchasing two Dell PowerEdge servers and an MD3000i iSCSI PowerVault. They are replacing 5 year old PowerEdge servers that are clustered with an old PowerVault as well.

Our goal is to make sure we have 100% up time during hours of operation (12 hours of the day) and make sure all files are accessible and users are able to authenticate to the Active Directory domain.

We will be installing Win2K3 64-bit Enterprise Server on them.

The servers were originally clustered to have a shared namespace so that if either authentication server goes down, users still have access.

Now, MS doesn't recommend clustering Domain Controllers and with the problems I've witnessed with the current clustered servers, I want to stay away from it with the new ones.

DFS seems like a better choice but with iSCSI technology, which I'm not very familiar with, I am getting a bit confused at how it works and what my solution might be for keeping files accessible. I'm not sure if iSCSI can allow two machines to access the same logical drive like clustering can or if I am supposed to create some shares on one server, some on the other, and use DFS without replication (since it's not needed as the data is all on the iSCSI array).

So, finally to the point, can anyone advise as to whether DFS is a good solution (and if what I described can even work with iSCSI) or if there might be a better solution out there considering I'm using iSCSI?

Any links or advice would be much appreciated!

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All Answers

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Read here..

Though this is for 2003. It might give you a few pointers.

Distributed File System Technology Center

The Distributed File System (DFS) technologies in Windows Server 2003 R2 offer wide area network (WAN)-friendly replication as well as simplified, fault-tolerant access to geographically dispersed files. The two technologies in DFS are as follows:


DFS Replication. New state-based, multimaster replication engine that is optimized for WAN environments. DFS Replication supports replication scheduling, bandwidth throttling, and a new byte-level compression algorithm known as remote differential compression (RDC).

DFS Namespaces. Technology that helps administrators group shared folders located on different servers and present them to users as a virtual tree of folders known as a namespace. DFS Namespaces was formerly known as Distributed File System in Windows 2000 Server and Windows Server 2003.

If you are using Windows Server 2003 R2 and want to keep folders synchronized, we recommend using DFS Replication instead of FRS. DFS Replication system in Windows Server 2003 R2 has many benefits over File Replication Service (FRS), including improved management tools, higher performance, and delegated management.

For information about other Windows Server technologies and services, see the complete list of Windows Server 2003 Technology Centers.

Please post back if you have more problems or questions.

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by jnpolizzi In reply to Read here..

Thank you for the reply. I'm still confused on what to do really.

For DFS, it's meant for separate servers which means I create some shares on one server and some shares on another server but, since they're all on the same iSCSI device, I don't want them replicating as this would be a waste of drive space.

Is there a way to have shares act the way they do in clusters? Meaning, two servers share the same SCSI volume and share a common namespace for the file shares on it. When one goes down, it's seamless. And there's no need for replication since they both share the same volume.

I need this same behavior except without clustering! We only have two servers and I don't feel it necessary to move the two domain controllers to other boxes just so that I can cluster two file sharing boxes. After my experiences clustering domain controllers, I don't want to continue doing that in the future. It was a headache I inherited and I don't want to continue with it.

So, can DFS share the same iSCSI volume between two servers so that there's no need for replication but still have namespace/share redundancy if one of the domain controllers goes down?

Thanks for any insight.

P.S. I have Win2K3 R2 Enterprise and 2K8 Enterprise available to me (x86 and x64 versions).

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