I found this thread which nearly describes exactly what I want to do. I have 8x2TB all pretty much full, and an empty 2TB and 3TB drive. By the info given in the above thread I'd want to create an array with just two drives, the empty 3TB as parity and the empty 2TB as data. Once that is established, copy one 2TB drive to the data drive and then preclear it and add it to the array... repeat 8 times. Seems straight forward enough however time consuming. My question is can I keep all the drives plugged in and accessible? I read the OP in the last thread nearly lost all his data just by having the drives plugged in. Do I need to connect it externally?

 

Thanks for any help,

Ryan

I would strongly recommend doing the copy over the network, even though it will take much longer. Reason being, as you populate the data on the server, you will still have the current 2TB you just copied intact, and can run file compare utilities and stress test everything before you actually delete the source drive by preclearing it. That way you know you can save and retrieve files over the network to your newly built server instead of finding out after you've erased the data that you have a bum stick of ram or something else silently corrupting your files.

 

The BEST method would be to keep your existing 2TB drives as backups, and store them in a safe place. Data you don't want to lose should never exist in only one physical machine. You would do well to pick up either 2 more 3TB drives, or if you want some slack space on the unraid box, 2 4TB drives. Yes it's expensive, and you already have all the parts you really NEED, but how much is your data worth to you?

What's your end goal?    If you're trying to use all the drives, then you can simply upgrade the parity drive to 3TB [Do a parity check first, to confirm all is well before you start];  then simply add the new 2TB drive to provide additional storage.    No copying of data necessary.

 

If the reason you're upgrading parity is to replace some of the drives with larger drives, you can still do as I just suggested ... then simply replace drives one-at-a-time and let UnRAID rebuild the data onto the new, larger drives.

 

You might want to consider buying a 4GB drive for the new parity drive, however => that will let you use up to 4TB drives as you increase the array's size in the future.

 

What's your end goal?    If you're trying to use all the drives, then you can simply upgrade the parity drive to 3TB [Do a parity check first, to confirm all is well before you start];  then simply add the new 2TB drive to provide additional storage.    No copying of data necessary.

Did you read the thread he was referencing? It implies that he has 8 2TB drives currently formatted NTFS, and wishes to migrate that data to a newly built unraid server. Your reply makes no sense in that context.

What's your end goal?    If you're trying to use all the drives, then you can simply upgrade the parity drive to 3TB [Do a parity check first, to confirm all is well before you start];  then simply add the new 2TB drive to provide additional storage.    No copying of data necessary.

Did you read the thread he was referencing? It implies that he has 8 2TB drives currently formatted NTFS, and wishes to migrate that data to a newly built unraid server. Your reply makes no sense in that context.

 

Obviously I missed that.  I saw the "I found this thread ..." but missed that "this" was a link 

... clearly I agree with the process outlined in that thread [since I wrote it  ]

Sorry for the confusion, and not making the link more evident.

 

The 'server' is already existing.... just a Windows machine on the network running drives. So this will be converting an existing server to unraid rather than migrating drives to a new server, just in case the specifics matter.

 

The vast majority of the data is my blurays I put on there for htpc use. I certainly wouldn't call it critical data so I don't see the need to keep 1:1 copies off site. I just want to save some time and aggravation restoring the data if I lose a drive. I do have a USB HDD dock that I can use to transfer to data from the existing drives to the array and to prove a good copy before I preclear them and add them to the array. I like the idea though of starting with a 4TB parity drive now, I might consider that vs. the 3TB.

Another advantage of buying a 4TB drive for parity is you'll be able to start off with 5TB of available space (your 3TB and 2TB drives) ... which will let you copy 2 complete 2TB drives worth of data;  then pre-clear and add those two;  then do 2 more;  etc.    More convenient than one-at-a-time ... AND it lets you add 4TB drives to the system as you elect to expand the capacity.

 

Referring back to the original question then assigning the disks to the unRAID array will destroy their existing contents.  This case is different to that where disks already formatted for unRaID can be added without losing their contents.  The approach mentioned by OP is therefore the correct way to go. 

 

It is perfectly OK to have drives that are not part of the array plugged in to copy data off them.  In fact if you are going to do the copies at the Linux level from a telnet session this would give maximum performance compared to copying over the network.  You need to be aware, though, that doing so is more prone to user error by you assigning the wrong disk to the array (or pre clearing the wrong disk) and destroying its existing contents.  You need to decide if the gain is worth the risk of a slip causing data loss.