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Brad Morris
Asked: 2013-08-15 14:58:59 +0800 CST

Sharing storage between DFS nodes providing failover without failover manager

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I'm currently consulting for a small engineering firm that has been using a single server for all their domain needs and their management has got sick of not being able to access networked shares from the server when the ageing hardware fails

I've procured two new HP ProLiant servers for file serving purposes running Server 2008 R2 Standard, and reconditioned their old hardware to 2 SAN boxes using FreeNAS.

Originally while trialling a solution, I was running a DFS namespace with both servers as nodes. The primary server is connected to the SAN via iSCSI and then the replication service copies the files onto the secondary server (to local drives).

Obviously it wouldn't be possible (or not recommended) to connect the second server to the same iSCSI volume as the primary server because of split brain etc. It seems pointless to use the SAN in the first place if the primary server replicates data onto the secondary servers local disks, and I can't share the iSCSI target to share the data between servers.

I figured using a NAS protocol to connect the two servers to the FreeNAS box at the file level, and configure DFS on the servers to only use the secondary server if the primary server is unavailable. Instead of the servers seeing the drives as local disks (as they would using iSCSI), I was planning to map them as networked drives. Doing this at the file level seems to alleviate the issues with sharing an iSCSI target between two servers.

I'm no stranger to SAN/NAS devices and FreeNAS in particular, but using it in a deployment like this is something new to me so I'm not entirely sure if this would work, or how it would perform etc.

Is this the correct way to go about this?

All the guides for this I can find on the internet are for Virtual Machines, and have some sort of failover manager, so I'm not too confident about following those ideas without having failover management.

Thanks!

windows-server-2008-r2

1 Answers

  1. Best Answer

    You can present the same iSCSI LUN to multiple file servers if you've properly configured a Windows Failover Cluster for file services. In this case you'd not use DFS replication, though a DFS Namespace would still provide value.

    You can also get rid of shared storage all together and do DFS-R with local disks and put both members of the replication group behind a DFS Namespace.

    I'm not sure why you're trying to do some trickery here to make both DFS-N targets use the same shared storage. If you want to use the shared storage, just configure a failover cluster for file services and have them share the LUN.

    Edit: Since you're stuck on 2008 R2 Standard, you're going to have a bad time. Upgrade to 2008 R2 Enterprise and do failover clustering, or (even better) use Server 2012 where there are vast improvements to both file services and clustering, and where clustering is available in both versions (standard and datacenter).

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