More on NAS at Home

After re-reading my last post, I realize that some of you might have no clue what I’m talking about when I mention network attached storage (NAS). To use an oxymoron, this post is a follow-up primer.

The idea with a NAS is to centralize storage across multiple machines in a network. Instead of having to maintain numerous independent disk drives on the individual machines in a network, NAS places all key files in a central location and worries only about managing the NAS.  This concept is frequently used with server computers but can also be used with workstations. Microsoft Active Directory, for example, supports the concept of a roaming profile that allows your personal files to be stored in one consistent place regardless of what computer you login to. UNIX and kin can do something similar with automounts.

There are actually two main mechanisms for implementing centralized storage.

The storage area network (SAN) approach is a different approach than that used by NAS. A SAN storage appliance provides low-level storage “blocks” to the computers connected to it. The SAN device has no concept of a “file” only of an assortment of storage blocks assigned to a particular computer. SANs are frequently accessed by a separate, high-speed, fibre channel network but can also be accessed over Ethernet using iSCSI and other other protocols.

A NAS device, on the other hand, provides file-level operations. The device implements the smb/cifs protocol and/or the NFS protocol in order to provide file-oriented services to Windows or UNIXy computers (respectively).

If you have used a traditional Netware or Windows-based file server you have used a NAS device. There are much cooler devices now, however. Isilon, for example, makes very clever clustered storage NAS devices that allow multiple NAS nodes to replicate data in a fashion that provides redundancy and high-availability at much lower cost than SANs and many other NAS devices.

The Linksys NAS 200 device that I talked about in the last post is a dirt-cheap home NAS device. It is not particularly fast nor does it offer much sophisticated functionality. Its security model, for example, is very crude. I run a Windows domain controller at home but the NAS 200 does not integrate with AD-based security. To avoid authentication hassles, I simply allow the guest (any user) to have read/write access to all the shared folders. Fine for home (where things are protected with a perimeter firewall and with secure wireless access points) but not fine for a more public network.

I installed the Linksys appliance in order to provide a backup destination for the 6 computers that we have strewn throughout the house. Using the appliance means that I don’t have to dedicate a general-purpose computer to this task. Additionally, Linksys has figured out how to set up Raid and how to automatically perform various recovery operations all using a simple Web interface. It would have been much more complicated for me to figure this out myself.

The one last piece of the backup puzzle that I’d like to implement would be to add some form of offsite storage. Ideally, the NAS 200 would, itself, backup files to some Web-based storage provider. Since it doesn’t, I might have to implement this myself with some type of periodic job that detects new files on the NAS and copies them to a service during off hours.