Pros: automatic system backups, small, quiet, inexpensive, runs linux
Cons: not for the network novice, not the speediest, drives must be empty to start
The bottom line: It does what it is supposed to do, and does it fairly well, for not a lot of money.
*pssst* hey buddy... come here... soOOOooo... got all your files backed up? NO?!? Come on, you know better! One worm, one piece of spyware, one failed hard drive, and *poof*, gone. All those digital pictures you took of your vacation to the Grand Canyon and your new baby... gone. Man, your wife is going to kill you. What's that you say? CD-Rs??? You gotta be kidding me!!! Yeah, like you're really going to do that every day.

Generally speaking, I don't get too excited about network equipment - even though I'm a nerdy, geeky guy, I just don't find routers, switches, hubs, and servers sexy. Sorry.

But I *am* excited about the NSLU2.

Why?

Last night, while I was sleeping, my NSLU2 backed up every computer in my house. And you know what? It's going to do it again tonight.

Before I continue, a warning: If you are unfamiliar with home networks and Windows networking - this road may not be for you. Confusion lies ahead for those that don't know a workgroup from a support group. So, please keep in mind that my rating is based on the user having some prior knowledge.

So, what exactly is this thing?
[jargon free version]
The NSLU2 is basically a tiny little computer (about the same size as a pack of recipe cards) that sits on your home network that, when connected to 1 or 2 hard drives (via USB), allows you to use it as a place to store files. In addition, you can set it up to automatically backup every computer on your network.

[jargon on]
The NSLU2 is a small Network Attached Storage device that uses hard drives connected via USB 2.0. Out of the box, it only supports SMB (i.e. SAMBA, i.e. the protocol that Microsoft networking supports automatically). It has an Intel IXP420 Network Processor in it and it runs BusyBox linux. It uses the EXT3 file system on the attached drives. All this in a cool little box and surrounded by a happy little Linksys style user interface.

There are a few really comprehensive reviews on the net (most notably the one at www.tomsnetworking.com) - but I'll give you the highlights, since you are already here.

Here are the specs from the user manual:
Standards: IEEE 802.3, 802.3u
Protocols: SMB/CIFS over TCP/IP
Network Port: One 10/100 Mbps RJ-45 Port
Cabling Type: UTP CAT 5 or better
Topology: Star
LEDs: Ready/Status, Ethernet, Disk 2, Disk 1
Switches: Power, Reset
Dimensions: 1.08" x 5.31" x 3.78"
(L x W x H) (27.5 mm x 135 mm x 96 mm)
Unit Weight: 185g
Power: 5V DC, Maximum 2 Amps, 100-240V AC, 50-60Hz

Some limitations:
- You can have at most 2 drives connected
- The drives cannot contain any data the first time they are connected to the NSLU2. It must put its own "secret" file system on it (which just happens to be Linux EXT3) - so, you can't swap drives between the NSLU2 and a Windows box (unless you load an EXT3 driver on your Windows box). If you require this, then you might want to look the Netgear box (WGT634U)
- It has been reported that some external drives don't work (Seagate drives in Seagate's external enclosure). EDIT: I see now that many people are using the external Seagate drive with success.
- It isn't high performance - but for $75, you didn't really expect it to be, did you?
- If you don't know how to set up a small Microsoft network (network drives, sharing, etc), you may need some help getting things set up.
- there are some files that should not be stored on a network drive, for example, as one user found out, Outlook files.
- The NSLU2 does not like to be put on a hub - use a switch instead.

Some cool things you can do besides just serving files:
- Schedule backups from any shared drive on the network to the NSLU2
- Schedule backups from the NSLU2 to any shared drive on the network
- Schedule backups from one disc on the NSLU2 to the other (poor man's raid).
- Back ups can be full, incremental, or "synchronized" (i.e. if you delete a file from the source, it is deleted from the backup).
- Automatically schedule "scan disk" runs on the attached discs (although you can't access the data while it is scanning)
- Create password protected user groups (e.g. you can give your kids their own storage area, with a quota, and restrict access to your own area where you store your, um, quicken files, yeah, that's it).
- Access the storage area via HTTP (even externally if you let it out your firewall - eeek!)
- It will send you an email if it has a situation that requires "administrator attention". (I'm not sure when that is...).
- It also supports flash storage as well, if you are excited about that kind of thing.
- Schedule the NSLU2 to shut down and start up a preset times (although it doesn't seem to shut down the connected hard drives)

I know, I know... you can do all this with an old computer and a RedHat install CD... yep. You are right. Did I mention that from the time I took it out of the box to the time it was serving up files and backing up data was exactly 22 minutes (including 10 minutes of format time)? Did I mention that I didn't have to read a single README file to get it working? Nor did I at any time have to recompile the kernel. Did I mention that it is absolutely silent (except for the noise of the hard drives)? Did I mention it was only $75?

As far as speed is concerned, I found it to be acceptable. Not fast. Just acceptable. It is faster than accessing files on say, a Windows 98 box over the network, but much slower than a real disc inside a pc, or even a disc connected to a pc via USB 2.0. As a point of reference, it backed up 20G of data off of a Windows 98 box in a little under 4 hours. Reading files seems to be substantially faster than writing them. I stored some mpeg2 video on it and streamed it from my Windows 98 pc to my ReplayTV (like a Tivo, only better ;) ) and it kept up just fine - no skips or delays. I can bring up a 2MB digital photo in about 1-2 seconds.

The setup is fairly straight forward. As with most little network boxes, it has a default address (192.168.1.177) that you can point your browser to and access the web based setup utility. Once you log into the Administration page, you can switch it to use a different IP (or use DHCP, which makes it exciting when you need to find it after a reboot - I love a mystery!). It does come with a little setup utility (for Windows) that helps you find it the first time and get some basic things set up. You can do everything through the web interface though. The GUI will feel very familiar to those of you that already have Linksys gear. Be sure to change your passwords from the default (but you already knew that, right?).

The backup setup is also a piece of cake. You specify where you want to backup to and from and when to do it. You can specify a backup occur every day at a given time, or on a particular day of the week. You can schedule multiple backup jobs with different from/to/when parameters. If you want to do a backup more than once per day on the same files, you have to create separate backup jobs for each additional time (for example, one job goes at 12pm, and another identical to/from job goes at 12am). The backup configuration can be downloaded/uploaded to/from a binary file. If you choose to mirror disk1 to disk2, it will destroy all the data on disc2. You can only backup (1) from a given folder on the NSLU2 to a shared network drive and path, (2) from a shared network drive and path to a given folder on the NSLU2 and (3) from disk1 to disk2 on the NSLU2. It might be nice to be able to just backup parts of disk1 onto disk2, but no such luck. If you choose not to mirror disk1 to disk2, you can use both disks as storage space (duh). While the NSLU2 is doing a backup, you can still access the data on it, and it seems to remain fairly nimble. It appears to give priority to the incoming requests over its internal backup traffic.

One thing that is obviously missing is any kind of useful logging. The only log it has is one for recording backup job status (and it only gives start and stop times). I'd like to see some security and statistics logs (failed logins, quotas exceeded, quotas utilized, transfer rates, you know, geek stuff), and I'd like to be able to save the logs to disc (I do have 400G, for heaven's sake). Maybe someday.

I keep my NSLU2 mounted as a network drive on my Windows boxes, and have assigned a drive letter to it ("N:" in case you care) and have it automatically reconnect at bootup. I moved the "My Documents" locations on all the PC's to that network drive and store all our files on it. I also keep my NLSU2 and drives on a small UPS that I got free after rebate.

They want you to use Maxtor's (over priced) USB drives and when I bought my NSLU2 they were offering a $20 rebate if you bought one (*yawn*). I just got a couple Seagate 200G internal drives and put them in generic USB 2.0 enclosures that I got for $25 each. Worked like a charm. I like the Seagate drives because they are really quiet and have a 5 year warranty (but that's a different review isn't it?).

So... back to the Linux thing. I know you want to fiddle. I too feel the pull of the techno-jones begging me to hack, fiddle, and disassemble. This thing runs Linux, right? As we speak, an army of Linux gurus are busy hacking this little box. So far, they have figured out how to put NFS on it, run an iTunes server on it, and how to create new flash images for it. More features are sure to come shortly. Hack away.

Let me bottom line it (in more than 30 words): it is not a do-it-all NAS. It isn't super speedy and it doesn't have a lot of bells and whistles. But what it does, it does well and it doesn't cost a lot. If you have a little network knowledge, it's easy to setup. Buggy? Well, it's a little rough here and there, but fully functional. Even if you just use it for backups, it will still be $75 (plus drives) well spent.