External LaCie 4TB Raid won't mount

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.

There is a 2TB limit with MBR (Master Boot Record), but even a larger drive can be partitioned. So a single 4TB (biggest on the market) drive will look like several drives.
External drives that are bigger than 4TB are really several physical drives combined by an array.

RAID 1 requires optional SCSI drives, cables, and even software?
http://support.dell.com/support/edocs/systems/ws670/en/ug_en/before.htm


Add on SATA 3 cards to PCI are not a good idea if you are looking for speed. They just bottlenecks the throughput.

You have a failed RAID array. These guys do raid recovery remotely over the net... http://FreeDataRecovery.us

It is time to check the WARRANTY status of the disk-drive.
If the warranty has not yet expired, exercise the warranty, to get it repaired/replaced, at minimal cost to you.

Otherwise, open the case, remove the "dying" disk-drive, buy a new, compatible, disk-drive, and "transplant" it into the case, to create a working external storage device.

Did you try LaCie is the premier manufacturer of high quality digital storage.

theres a possibility that the hard drive is not formatted for mac.
-check if the raid configuration set on the hd is compatible with the mac that your using.

Hi,
You don't specify whether previously on your USB it was the same lacie external or whether it was a different external drive. It sounds like you were using a different external drive, most likely a single drive.
You've specified that you've got your lacie setup in raid 5. Raid 5 gives a very good read spead and a good redundancy for incase a drive fails, however it's write speed is very very slow.
It will be much slower than a single drive on USB for writing to it (i.e. backups), but you should see a huge performance boost in reading from the drive than your previous usb.
If you need it to be faster, you would be better suited looking at configuring it for one of the following raid setups:
Raid 0: striping (not recommended for backups) - data is split over all drives, however if 1 drive fails you lose all data.
Raid 10: striping + mirror . half the drives are striped (like above), but the other half mirror the striping half so if one drive fails there's a backup of it. You only get half the disk space though, so if you have 4 x 1Tb drives, then you'll only get 2Tb of space.

I am not really sure where to start here because I am a little confused about your setup here. It seems you made a great choice to keep Windows and your data on separate drives. Your primary hard drive is a really fast SATA Raptor drive, which is great, but I would never use an external hard drive for general everyday data storage. Many will probably disagree with what I have to say, but external hard drives should really be used only for temporary backup. I would never suggest using an external hard drive as your only copy of your data or for regular everyday use. There are several reasons for this:
1. External Hard drives are generally slower than Internal Drives.
2. Many of them come preformatted with Fat32, so you are limited to files no larger then 4gig.
3. They are more likely to fail because they are normally subjected to a greater likelihood of accidental bumping or dropping.
4. Many external drive enclosures are not properly cooled for continuous usage and thus lead to premature failure.
5. You often have no idea what brand of hard drive is actually inside the enclosure.

Don’t get me wrong, external hard drives are wonderful and I use them all the time. I have three LaCie 160 gig drives myself that I use all the time for temporary backup, but I rotate them so that I have 3 consecutive backups and would never use them (not just Lacie but any external drive) as my only backup or as a primary data drive. And yes, I have had to replace a few of them due to failure.

So to address your specific questions:

What went wrong? –
1. Bad Cable - Well it is probably unlikely, but I would first try another USB cable just to make sure the cable is not damaged.
2. Power Supply - Try another power supply if you have or can borrow one.
3. Controller Failed – The Controller inside the Lacie has failed.
4. Drive Failure – The Hard Disk inside the Lacie has failed. Drives typically have an average 5 year lifespan, some last longer and some can fail much sooner. Unfortunately, you rarely have any warning, thus the need for backups.

you may need to get a new driver for that lacie from their website..

support downloads, model o/s