File Replication accross WAN link


We have two sites connected via static VPN link over a T1 WAN connection. Site "A" is the corporate office which has the main file server where we have the file store for the organization. This site also maintains the Windows 2003 domain. Site 'B" is a field office with no local domain controller or file storage of their own. When they log into the network, they are doing so from our domain controllers. We prefer that site "B" uses site "A" file server to work from and store the production work files as this location has the backup services.


The connection is slow from site "B" to site "A"s file server. Navigating the directory structure is difficult at best. They normally copy files locally to work from which causes problems when they copy them back because we have multiple users working on the same projects. Over writes are a major concern.

Solutions? What we need to accomplish is to have the file structure replicated at both sites. If someone opens a file on either replicated server, it locks the other file out as "read only". We are already planning on integrating another DC at site "B" to enhance network response times for Internet browsing, logon and print services.

How is this best accomplished? Would DFS help to some extent?
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Microsoft claims dfs will solve this problem and on paper it seems to do exactly what you require, however my experience of DFS has been far from positive especially if the filesystem gets reasonably large and/or has some kind of virus protection. (virus scanners modify the timestamp on files so they end up having to be re-synchronised). What type of data is being synchronized? Could a CVS system work?
Actually, there is an interesting class of network accelerators that can resolve this problem.  The recommended equipment depends in part on the routers you are running, so it would help to know that.  Cisco calls their unit WAAS.  Riverbed Steelhead is another popular one and Juniper Networks has another.  Depending on which you select, they can provide extreme bandwidth benefits.  They may also support maintaining a synchronized image of files at the remote site for "near LAN" performance.

You described the perfect application for these units.  And, they can be cost effective as compared to installing and supporting remote servers.
jefferybushAuthor Commented:
Thanks, Static and RG. We use a Cicso 1721 here (site A) and a 1720 there (site B). We have a Cisco 515 firewall here and a 506E there. I think the remote server is needed anyway as they are using an old XP box as a local file storage and print server. That utility box only has 10 net connections max (because of the XP limitations).
Cisco has two versions, network modules and standalone appliances.  The network modules are very cost effective because they install in your router and do not have any maintenance costs over and above what you are paying for your router.  Unfortunatly, my little bit of research says they don't work with your routers.  So, you need the appliances.  And, you need 3 to run which is one for each site and then a central manager.  I'd conatct the various vendors, or your VAR, and get specs and quotes.  If they can make it affordable, it is a wonderful solution.

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jefferybushAuthor Commented:
Sorry I haven't been keeping a firm handle on my question, I find it irresponsible when the question isn't closed and appropriate points awarded. Thanks to both of you for responding. The WAN accelerators are currently being reviewed.

Once again, many props to EE for providing valuable info to the "not-so-tech" savvy.


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