Evaluating Remote Storage and Backup Options

I'm setting up three remote offices, all running Windows 2000 for the server and client OS. Each office houses 30 employees, which is too few to build an expensive storage-and-backup server but too many to have the remote offices continuously use a slow (i.e., T1) WAN link to access data at the corporate office. Other than storing a small Network Attached Storage (NAS) box and tape drive in each remote office, what alternatives do I have?

You do have a few alternatives for placing a storage infrastructure in these remote offices, and some of the alternatives are fairly recent developments. One option is to implement some form of data caching at your remote offices. By caching directories remotely, you maintain the same level of performance you would typically see when you access the data locally. This option typically uses an aggressive compression scheme when transferring data, which helps to minimize any negative performance on the WAN. This option can also use 2-way differential transfers so that when a user modifies a file at a remote office, only the changes are sent to the corporate office storage system.

Enterprise file-storage vendor DiskSites offers a data-caching solution called W-NAS that might also suit your needs. W-NAS consists of two or more appliances (depending on your number of remote offices), with an appliance residing at the corporate office and one residing at each remote location. The W-NAS FileCache appliance at the remote office works with the W-NAS FilePort appliance at the corporate office to keep commonly accessed data easily available to the remote office. The W-NAS FileCache appliance supports both the Common Internet File System (CIFS) and NFS protocols.

Another data-caching solution on the market is Cisco Systems' Cisco Content Engine Network Modules for some of its routers. However, these solutions target mostly Web and data streaming services to the remote office.

Another option is to provide data replication between the remote office and the corporate office, although this option addresses only the backup concern. By replicating commonly accessed directories, you can centralize your file backup process at the corporate office; however, you still need enough remote storage to replicate the data.

For data-replication solutions, check out VERITAS Software's VERITAS Volume Replicator. You might also consider using Win2K's built-in File Replication Service (FRS), although it can be cumbersome to manage. Of the data-caching and data-replication solutions mentioned above, only data replication is geared toward providing the remote office disaster recovery in addition to faster access to data.