Mirrored Storage Array LUNs for fault tolerance

Posted on 2010-11-15
Last Modified: 2013-11-14
We have two Dell MD32000i storage arrays. Our main Win 2K8 R2 file server shares a LUN on SA1 for our user files. I then robocopy the data to a LUN on SA2 each night (takes about 3 hours) as a backup, ready to cutover if we have a failure of SA1. Why couldn't I mirror the drives at the File Server level for fault tolerance? Is this a crazy idea? There may be a slight performance hit, but it will protect me gainst the failure of either SA, one of which is housed in a remote building but still on the LAN.
Question by:goodvibes
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LVL 42

Expert Comment

ID: 34142797
You can use DFS replication to keep everything up to date on the other server. I think that's a better option than using dynamic disks to create a RAID1 set, because I hate dynamic disks, and using RAID1 won't leave you with an operational server in case something goes wrong with your sever, which is more likely than a failure in your storage array.

Expert Comment

ID: 34148905
DFS is good.  It's also asynchronous, which is probably what you would want.  You'd want another server at the remote site too.  That would also let users access the data depending on which site they were at, which would cut down on latency and network traffic.

If you had a sychronous mirror (or RAID1, RAID10 volume) that spanned multiple data centers/locations.  You then get into the fun stuff SAN admins have to tackle - Latency.  Roughly add 1ms latency for every 100 miles you span - that can vary depending on the # of hops, type of connection, etc).

I agree with Kevinsieh on DFS.  It would also give you better redundancy/fault tolerance.  You could have an antire server fail and still be up and running.


Author Comment

ID: 34150575
This is not really what I'm after. We are only one site, I am only looking to mirror the LUN in the most efficent manner possible, not the server. Although I will check out DFS, we tried it back in the server 2000 days with mixed success and abandoned it.
LVL 42

Accepted Solution

kevinhsieh earned 250 total points
ID: 34150961
We're suggesting DFS Replication because it gets your LUN and server mirrored. Something on your server is more likely to break than the MD3200i. DFS Replication is much, much better than the File Replication Service that is in Windows 2000.

Otherwise, you can probably to use dynamic disks to mirror the data to both arrays. I would start with a test volume first, and make sure you can take the volume from 1 MD3200i offline and then read off the other copy.


Author Closing Comment

ID: 34151012
Not what I was originally after but provides avenues to explore

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