Do not buy this if you care about your data!
The disk is sold as a backup solution. Therefore it should be fairly easy to get your backed up data in case of any failure.
Unfortunately, this is not the case.
I had the disk running in RAID1 mode (half size, 2 mirrored disks) for about 2 years, without problems. Then, after a power failure, the enclosure died.
LaCie told me to send the whole disk to France (I'm in Europe) to have it repaired, but without any guarantee. Since I care about my data, I did not take that risk. LaCie didn't offer any other option or help.
Since the disks seemed to be ok, I put the into a USB enclosure to try to hook them up to a PC or Mac. Didn't work, the disks use Linux.
The I Installed Linux on both my Mac and PC and tried to connect the disks: some of the partitions showed up by using Linux shell (I am not a Linux pro and this was supposed to be an easy backup solution), but not the Data partitions.
Only after searching for a couple of days on the net, and learning a lot about Linux on the way, I found a way to mount one of the disks:
connect the disk to your Linux machine, run the shell and type:
sudo mdadm --assemble --run /dev/md0 /dev/sdb2
This is a command that mounts the RAID (sdb2), so you can access it from the Linux desktop.
It helps to have another disk at hand, with a different file system that works with your PC or mac, to copy your data :-)

My advice: Never again! Backup should be easy and reliable, one shouldn't need a Degree in Linux to get his data back!

Don't buy this or related product if you value your data
I'm on my second 2Big Network, a replacement for one that died last September. My current unit is in some indeterminate state where the web interface says "reconnect later" and no shares are available. It will not reset to hardware defaults. It started acting up a week ago, generating errors when reading files. Fortunately I have a back up of the data that is on it. LaCie tech support hasn't opened my ticket since I posted on their support site last week. In the past I found their attitude towards your data rather cavalier. They require you to send the entire unit back, with no recourse for saving data. I managed to pull the data of my first unit by mounting the individual drives under Linux. What else can I say? Apple AFP doesn't really work right. The unit is slower than tar. It's internal backup to external device feature is even slower. The user names and groups don't really work right, so I set all the shares to public. The built in RAID is nice, but useless if the entire unit croaks instead.

I'll be pulling the unit apart and salvaging the drives and data. I'll build my own NAS around a Mac Mini. The LaCie chassis is going to the gun range for target practice. I'm done with it and done with the company.

Save yourself problems and headaches. Do not buy this product or anything from LaCie.

Broken by firmware update
This drive is garbage. The latest firmware update (2.2.3) corrupted the file permissions. Now I can't access any of the files through ftp, afp or smb protocols, so there's no way to copy them off the drive (except one at a time through the web interface).

Lacie tech support says "reset the drive," which destroys all the data on the drive, but can't tell me how to get the files off first.

In summary, don't buy this drive.

9 Months and DEAD!! Buyer Beware!
I purchased my Lace 2Big Network (1Tb version, 500Gb in RAID 1) in October 2008. The unit is now on it's last legs. It was working fine for the first 3 months then one of the hard drives failed (Drive 0, it was a Seagate). Contacted Lacie and was told that I had to ship the ENTIRE unit back for repair. I thought that was odd since only one drive failed. I didn't want complete strangers looking at 98.6Gb of my personal data so I bought a spare 500Gb Lacie drive (Hitachi Deskstar, funny that it wasn't a Seagate) and was up and running again. (obviously that was the issue, hardly in need of shipping the entire unit back). BTW, when one drive is completely dead, the entire device is unusable. You better have either an external SATA data cable to pull your data off, or you need a spare Lacie drive bay lying around and hope it will work. Then you can pull off your data and format / ship the unit back. Ridiculous!

With the new 500Gb Lacie drive installed (which I bought at my own expense) the unit worked fine for about 2 months. Then the front LED stopped displaying anything. The whole 2Big unit was still functioning at the time. Then the fan died a week later. Once again I was informed that if I wanted Lacie to honor their "Limited" warranty I would have to send the entire unit including the original drives in for RMA. When the unit dies I can't access the data so I am TRUSTING that Lacie's employees won't steal any of my 98.6 Gb of songs, photos, documents, Quicken files, etc... Are you kidding! Do they want the keys to my house also?

The Lacie 2Big was great when it worked. The web configuration was easy to use and it worked (when it did) well with the 3 Macs I have. AFP worked great (2 Intel iMacs, and a Intel Mac Mini all running OS X 10.5.7). But its not reliable at all. Lacie has terrible support page on their website. For a company that prides it self on Mac centered / designed products, there is more PC info for troubleshooting. Their return policy for defective parts is really bad. I don't feel comfortable sending them my data. I can not recommend this product. I would say for almost the same money buy a Netgear ReadyNAS Duo.

As for my Lacie 2Big Network unit, I will be removing the SATA drives (voiding the useless "Limited" warranty) reformatting them for use in a new Netgear ReadyNAS Duo, and smashing the unit with a sledge hammer. It's a really nice looking 0+ paper weight.

Drive failed, again.
I have had this product for exactly one year, today being the 1 yr mark.

This device has now failed twice in one year and I am about to go through the warranty nightmare again. Customer service is horrific and could care less about the folks who get stuck with their gear.

When I pressed a customer service rep on why it would be difficult for me to send in the whole unit for repair since its my sole point of mass storage for important data (I have no other storage device to hold everything), i was offered this piece of advice:

"...make sure that important data has duplication on more than one completely separate device"

In other words, completely apathetic to my situation and plainly stating that you should not count on our dual drive device to offer you data security.