DFS and SAN thoughts

D

DarkOne_BW

Limp Gawd
Joined
Apr 21, 2002
Messages
472
Recently I hired on at a new job, and after taking inventory of some of the equipment I'm at a bit of a crossroads. This new place has, sitting in the floor (read: barely unpacked) a SAN solution from HP. From what I've seen this includes an 8 port FC switch, the necessary GBICS, the drive array, and the FC cards for my servers.

In the past I've worked with DFS for balancing between multiple servers to increase availability, but I'm wondering about adding the SAN piece to the mix (something I've never deployed).

Here's the question for anyone in the know: Is it a good idea to tie DFS (2003 R2) and SAN technologies together? If so, what additional pieces are involved?

In my ideal scenerio, the SAN would host the files, but the network load would be distributed across the file servers tied into the SAN. Remote site servers would replicate the DFS overnight, giving my users mobility from site to site but still keeping the WAN links free from the bulk of the network's traffic during the day. Would I simply just not enable DFS replication between the servers directly attached to the SAN?



.....and my apologies go out to everyone who was looking for a job change in Oklahoma. We had a new hire before I could even post the opening here for my old job. :D
 
I've always loved storage, but I've never found a site / place / person to teach me about SAN's. Just my luck to find one laying around my new job.

Congrats on the new job though.
 
SAN and DFS are kind of seperate beasts. If you are looking to centrally manage you storage for your servers, the SAN is what you need. Also, SANs come in handy when creating Windows clusters and it will function as shared storage between the two nodes just by adding a HBA to the servers.

Depending on your solution, you can replicate a SAN to a remote site for high availability. But, if you only have a single switch and storage chasis, then this probably isn't an option.

SANs are an enterprise disk solution that helps reduce the amount and costs of individual arrays. If you are wondering what you should do with, find a place in your environment that needs this type of solution.

As far as DFS goes, it works on top of any storage solution transparently. So, your idea of using it accross sites would work just fine if you can't use SAN replication.
 
If your looking for better availability you should look at Microsoft Cluster file/print server setup. That way you don't waste space by keeping multiple copies of the same data on expensive SAN space.
 
My thought is to not have to have "multiple copies of data" on the SAN. The idea would be to have 3 servers all connected to the SAN device (three "fingers in the pot" accessing a single repository of data). On these servers I would configure DFS to be non-replicating, so that any one of the three servers could change a file. The primary job would be hosting user documents.

As an additional benefit, I'd turn on DFS replication to a server off-site for backup and increased availability (in case the SAN dies).

Any of you other net admins see a flaw in this thinking?
 
Well, if you are talking about shared storage between servers (or clustering) only one system can have access to a LUN at a time. If each server is getting its own LUNs then you will be fine
 
MorfiusX said:
Well, if you are talking about shared storage between servers (or clustering) only one system can have access to a LUN at a time. If each server is getting its own LUNs then you will be fine
Click to expand...


which is why you would use clustering instead of 3 servers and DFS. You can setup DFS as a cluster resource/share.
 
If you had three unrelated/non-clustered servers, you could add them to the DFS tree for easier access regardless of the disk solution. If all three servers are going to have unique content, then having LUNs on the SAN isn't a problem. If you are trying to create a fault tollerant system, then just cluster two servers.
 
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