My lacie 2big network 2 is not often found on the network during these two last week, Note that it was ok for the 5 pasts month. Today the same thing happen, after waiting for several minutes i restarted it, i tried for several times and finally get it, so the first thing i did is to back up all my stuffs. Then I try to update the Lacie, every thing was ok till at 100% when it stop here. And on the panel it is written not to unplug or restart. Now I here still waiting for something to happen... and so I decide to ask you for help. Thanks

You didn't provide details on what mode you were running or if this worked before and this is a sudden event. The manual doesn't appear to cover this situation of one blinking red light: https://www.lacie.com/download/manual/UM_2big_Quadra_EC_EN.pdf
but I found a YouTube video that may be helpful to you:
http://www.youtube.com/watch?v=V8KbtZYytC0

Most likely the problem you are encountering is due to the RAID mode the device is set in. Most RAID arrays utilize multiple drives of the same size, or with drives of differing size, they just use a portion of the largest that matches the smallest drive. When the device rebuilt the array it partitioned off a portion of the 4tb drive of the same size as the existing 500gb drive. If you want to use full capacity of both drives you would need to use JBOD mode, which just strings the disks together into a storage pool using all available space. This won't offer the data redundancy of RAID1 or speed boost of RAID0, but should allow using full space.

Backup any vital data before doing anything, then look for a switch on the back. Rather than RAID0 or 1 the options may be labelled Safe or Fast, but JBOD is usually still labelled JBOD, or sometimes Big. You can try just flipping the switch to JBOD and seeing if it rebuilds to use all space. If that doesn't work you may need to remove the 4tb drive, connect it to a different system and erase it to get rid of the 500gb partition, then with the Lacie set to JBOD reinstall the 4tb drive so it will add its full size to the array.

The safest option though would be to buy another 4tb drive, backup all data and install both 4tb drives with the device set to RAID1/Safe. You would only get 4tb of total storage, but it would mirror the data on both drives so if one fails the other will still have your data. With JBOD you won't have any auto-backup. If a drive fails the data on it will be lost.

The adress of the server error is 00:D0:4B:8D:1C:50. Has anyone a solution? and The message was " Something wrong with the volume CNID BD"

see if not the cord first because they get a short in them after awile.

I have the same problem too on my 2big form lacie . If I use 2x 1,5 tera disk in "fast mode" or in "big mode" my disk manager only shows 746 gigs available (it should be at least 2,5 terra).
If I use "safe mode" so my system can see 1,3 tera available, wich is normal for a raid mirror configuration.
I hope to find a solution quickly.

LED Indicators - LaCie 2big Network
The LED indicators above the drive bays and the front LED indicate drive status and activity.
During Startup

• Front LED – blinks red/blue until both disks are powered on, then turns solid blue.
• Rear LEDs – blinks red/blue until corresponding disk is powered on, then turns solid blue.

NOTE: If the device is not able to initiate the boot process following disk startup, the front is solid red.
During Bootup

• Front LED – solid blue
• Rear LEDs – solid blue

NOTE: If a disk is failing, both the disk’s corresponding rear LED and the front LED will be solid red.
During RAID Synchronization

• Front LED – solid red
• Rear LEDs – The LED corresponding to the original disk will be blinking blue and the one being synchronized is blinking red
• Once both disks are synchronized, their corresponding rear LED and the front LED will be solid blue.

Sounds like you may have been unlucky in starting the reformatting software for the drive. Goto the following link to check out the documentation for the product:

http://www.lacie.com/download/manual/2big_Quadra_en.pdf

check the date on ur system clock...

Hmmm, reseting worked on mine. Identical symptoms except light stayed blue, not red. Unable to power down.
Before trying to get the drive working I got the data off using the procedure in the second post of this thread:

http://www.linuxforums.org/forum/peripherals-hardware/126831-reseting-lacie-2big-network.html

You need a linux system running. Maybe a live cd will do. I installed on an old IDE drive I had.

I then rest the decive using this procedure from Lacie and my drive is working again. Worthless though, because I can't trust it.

The procedure below will reset the 2Big Network to factory settings:
IMPORTANT NOTE: Following the procedure below can ERASE ALL DATA on the drive. Prior to following these directions, verify important data is stored securely on a different storage device.
Switch the drive OFF. Once it has shut down, ensure the power switch remains in the OFF position.
If the drive is in the SAFE mode, move the RAID switch to the BIG mode.
PRESS AND HOLD the button on the front. MOVE the power switch to the ON position. The light on the front of the drive will start blinking.
Once the light stops blinking, RELEASE the front button.
When released, it will begin BLINKING AGAIN. When it stops, PRESS AND HOLD the front button. The light will begin to blink again.
When the light stops blinking, RELEASE the button. The drive is now resetting itself. Switch the RAID selector back to SAFE if desired.
To restore data if it was lost during the process, recreate the shares and users on the unit prior to the reset. Any firmware updates applied will need to be applied again.

check your network for conflicts, check power supply, fan and nic card, if your sure it's not the the drives inside the drive case, I have had 4 of these fail on me @work with different issues power supply nic card and both drives 4 units did the same thing and they were under warranty so when I got it back, I sold them and bought The Seagate BlackArmor NAS 420. no problems with them as of yet. Lacie get hot and components get hot and fail because there is not enough air flow I think.