Should DFS be used to sync wwwroot?

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+1 Q:

Should DFS be used to sync wwwroot?

I'm wondering if it's a good idea to use DFS to sync content across a web farm? Does anyone have any experience of this? We've used Robocopy in the past but found it a little patchy and clunky. Essentially we want to avoid having to make ten changes to content each time one file changes (this happens a lot since our site is old and usues classic ASP.)

From what I gather, DFS is usually meant for geographically seperated locations and used to make the UNC shares appear simpler to users and easier to manage.

What I'd like to achieve with it is to only copy content changes to one of ten servers which will be the hub. I'd then configure the other nine servers as spokes using FRS.

Any thoughts on this methodology or suggestions for better setups would be much appreciated.

+1 A:

If you're using Win2003 make sure to install R2, DFS replication is much improved and doesn't use FRS. It will do what you want, even over a LAN.

20th Century Boy 2009-04-28 11:37:12

That's what I thought, will the replication be easily configurable in terms of time between uploading a new file and it being pushed to the other content servers?

Beanie 2009-04-28 11:45:45

+1 A:

For performance reasons, don't point a web site to a UNC path. SMB file access is horribly inefficient and slow compared to pretty much any other file access method.

You can use DFS-R (via Windows 2003 R2) to enable replication between DFS-enabled shares, but definitely setup IIS to point to the share's local path, not UNC.

spoulson 2009-04-28 11:40:55

Thanks for that warning. My plan was to use the local directories (Always d:\WebData)Does this mean that the namespace is pretty much redundant in the scenario I'm proposing? If so should it be disabled, if that's even possible?

Beanie 2009-04-28 11:47:31

If IIS is pointed to the local path, the DFS setup itself is irrelevant. I imagine you'd utilize DFS-R to manage a web farm for either/both fault tolerancy or load balancing. The domain or host-based namespace approach is up to you, since you'll be the only one accessing it via UNC path.

spoulson 2009-05-07 13:23:01

Don't use FRS for this, it may get confused. Using DFS and another sync technique, such as Symantec Replication Exec, works fine. Make sure to create the correct site structure with IP ranges in Active Directoy so that the correct servers are chosen by DFS.

I tried that some years ago with FRS, when Windows 2003 was new (before SP1, things may have become better since then, but I'm not sure). FRS twice completely went nuts and deleted our files, not to talk from the amount of times it just clogged up and failed to recover itself. FRS also does only sync files which are closed, files which are left open are not synched (when doing log file collection for instance). FRS is fine in environments where you have a moderate amount of relatively small files with not too many changes going on on the server.

Lucero 2009-04-28 11:44:37

I'm slightly confused by this, are you saying not to use the DFS synchronisation (which I believed was FRS built into DFS?)If you're proposing using the Symantic tool, which I'll investigate, doesn;t that negate DFS as I only wanted it for the replication process as users will never use the Namespace since the primary purpose is only to synchronise IIS data which will be updated by FTP, hence the files will never be opened and I wont be synchronising our log folders.

Beanie 2009-04-28 11:52:49

What I'm saying is that using DFS in general is OK (with the "normal" caveats of using web sites on UNC paths), but not with the built-in synchronization which is FRS. Of course you'll get the best performance if you have a replication agent (assuming you're using the Symantec tool) on each web server synching to a local direcotry and use this as local web source directory.

Lucero 2009-04-28 12:11:55

Thaks, I'm beginning to understand now. However it seems that if I were to use some other agent like Symantc, there would be no point in me having DFS since the agent would do the part of the job I wanted DFS (using FRS) for in the first place. Am I following you correctly there?

Beanie 2009-04-28 12:20:13

Sorry for the delayed reply... but yes, you are correct. DFS can still be set up as distributed UNC share on such a replica, that's all I wanted to say. But in the case of web hosting without UNC-based web roots, there is no need for DFS anymore, right.

Lucero 2009-04-28 14:50:10

I have very recently disabled the UNC DFS as the site root on a server; under heavy load the site would become unresponsive to requests. Pointing the site wwwroot to a local drive and restarting IIS quickly restored the site speed. I have to recommend that if you go the DFS route, simply have it replicate to a local drive instead of using the UNC path as the wwwroot.

GTGreg 2010-01-04 03:54:00

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Should DFS be used to sync wwwroot?

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