I am in the midst of migrating data from my Drobo to a new unRAID box. My plan was to transfer enough data off the Drobo to free up a drive that I could then move to the unRAID box to create enough room for the next drive worth of data. It was working find until Drobo decided not to rebuild my array and allow me to remove a drive. I have less than 4TB of data left on the Drobo and a 4TB parity drive on my unRAID machine. Can I use my parity drive as a data drive to be able to move the rest of my data off my Drobo, then after I move all the drives from the Drobo, I can shuffle the data off the old parity drive and convert it back to being the parity? Is this possible? I know I would be without parity for a while...

Tools - New Config. Assign your drives with nothing in parity slot and former parity in a data slot. unRAID will format your (former) parity drive when you Start.

 

After you're done and have the drive empty again:

 

Tools - New Config. Assign your drives with that drive in parity slot and nothing in its former data slot. unRAID will build parity when you Start.

 

Good. I thought that might be the way to do it. So, to be clear, "New Config" won't clear/erase/format the current data drives? How will it know that the only drive that needs formatting is the parity?

 

Also, will the parity only need formatting, or clearing as well? (I wonder if it won't need clearing because there will be no parity to calculate...)

 

Lastly, if I ever wanted to rearrange the numbers unRAID uses (Drive x/Data x), is New Config the tool I would use? And would it force a rebuild of parity? Is there a way to reorder the drive numbers without rebuilding parity?

Good. I thought that might be the way to do it. So, to be clear, "New Config" won't clear/erase/format the current data drives? How will it know that the only drive that needs formatting is the parity?

After a New Config unRAID will recognise existing file systems on a disk.  The parity disk does not have a file system so unRAID will realise it needs formatting.

 

Also, will the parity only need formatting, or clearing as well? (I wonder if it won't need clearing because there will be no parity to calculate...)

There is no need to preclear it.  The prime purpose of preclear is to zero a disk so it can be added to an existing parity-protected array without affecting parity.  After a New Config you no longer have an existing parity-protected array. Having said that if is a brand new disk many users like to carry out a preclear of such disks just as a confidence test on the disk.

 

Lastly, if I ever wanted to rearrange the numbers unRAID uses (Drive x/Data x), is New Config the tool I would use? And would it force a rebuild of parity? Is there a way to reorder the drive numbers without rebuilding parity?

Yes - New Config is the way forward.  Parity is not affected by the disk order, so if you already have a valid parity you can click the 'Trust parity' checkbox to avoid a parity rebuild.  If in doubt as to whether you have valid parity do NOT check that box as it is better be safe than sorry.

Lastly, if I ever wanted to rearrange the numbers unRAID uses (Drive x/Data x), is New Config the tool I would use? And would it force a rebuild of parity? Is there a way to reorder the drive numbers without rebuilding parity?

Yes - New Config is the way forward.  Parity is not affected by the disk order, so if you already have a valid parity you can click the 'Trust parity' checkbox to avoid a parity rebuild.  If in doubt as to whether you have valid parity do NOT check that box as it is better be safe than sorry.

Thank you both for very fast/helpful replies.

 

Does the 'Trust Parity' checkbox come up as part of the 'New Config' process?

Lastly, if I ever wanted to rearrange the numbers unRAID uses (Drive x/Data x), is New Config the tool I would use? And would it force a rebuild of parity? Is there a way to reorder the drive numbers without rebuilding parity?

Yes - New Config is the way forward.  Parity is not affected by the disk order, so if you already have a valid parity you can click the 'Trust parity' checkbox to avoid a parity rebuild.  If in doubt as to whether you have valid parity do NOT check that box as it is better be safe than sorry.

Thank you both for very fast/helpful replies.

 

Does the 'Trust Parity' checkbox come up as part of the 'New Config' process?

Yes it will be an option when you Start the array after New Config.