Hi all,

 

I am planning to use Unraid for my new NAS. I have been reading a lot about it and it looks very promising but I am unsure about the best setup of my drives. The purpose of my system is to provide media to different devices in my house. Currently I have:

 

4 * 2 TB (empty)

4 * 3 TB (filled with 8 TB data in my current system)

3 * 4 TB (empty)

 

1) What would be the best configuration? I have been thinking about 2 options (or is there a better configuration?):

 

Option 1: (23 TB usable, 9 TB parity)

2 TB: 3 Data + 1 Parity

3 TB: 3 Data + 1 Parity

4 TB: 2 Data + 1 Parity

 

Option 2: (24 TB usable, 8 TB parity)

Mix all together en use 2 * 4 TB as parity

 

2) If I choose option 2, would I be able to start with all the 2 TB and 4 TB drives, assign 2 * 4TB drives as parity drives, copy all my data and then add all the 3 TB drives?

3) For the future, if I would add 5 more drives to option 2 in the future, would I be able to assign a third parity drive without losing my data on the array?

 

Thanks in advance

3) For the future, if I would add 5 more drives to option 2 in the future, would I be able to assign a third parity drive without losing my data on the array?

Unraid only supports 2 parity drives, and they must be as large or larger than any data drive. Each parity drive protects against the failure of 1 other drive. Individual files are not protected by parity, only the complete drive.

 

Dual parity is not available yet in the released version 6.1.9, it is available in the release candidate 6.2 series. 6.2 may go final shortly, but exact dates are not known.

I may have misread but you seem to add 4+4=8TB parity. It doesn't work that way. UnRAID doesn't add up drives for parity. So a 2x4TB will allow u to have max 4TB per disk on the array.

alright, seems like I misunderstood some things.

 

How about creating one array of:

4*2TB + 3*3 TB for data with 1*3TB parity

And one array of:

2*4TB for data with 1*4TB parity

 

Or would creating 1 array of all the hdd with only one 4TB parity disk also work? I am afraid the rebuild time would become too high, but maybe I am wrong on this.

You cant have 2 arrays unless you have 2 servers.

So one array with one 4tb parity drive and all your others as data drives.

You cant have 2 arrays unless you have 2 servers.

So one array with one 4tb parity drive and all your others as data drives.

 

oh come one, two arrays, that would be aweosme ; LOL

I am afraid the rebuild time would become too high, but maybe I am wrong on this.

Rebuild time is based on the size of the failed drive and the combined read speed of your drives. The only reason adding more drives increases rebuild time is if you do not have enough bus bandwidth to feed all your drives at once, i.e. more than 2 drives on an old PCI slot, or something similar. Rebuilding a drive will take roughly the same amount of time as checking parity.

You cant have 2 arrays unless you have 2 servers.

So one array with one 4tb parity drive and all your others as data drives.

 

oh come one, two arrays, that would be aweosme ; LOL

I think the idea of running unRAID in a VM inside unRAID and passing it a controller has been floated.

 

But for the OP, one array with the largest drive as parity as gridrunner said. Or go to 6.2 and have 2 parity drives if you want, but still just one array.

alright, seems like I misunderstood some things.

 

How about creating one array of:

4*2TB + 3*3 TB for data with 1*3TB parity

And one array of:

2*4TB for data with 1*4TB parity

 

Or would creating 1 array of all the hdd with only one 4TB parity disk also work? I am afraid the rebuild time would become too high, but maybe I am wrong on this.

I think you are over-complicating things - which probably because of the excitement.

 

Let me turn it over and ask you: WHY do you need 2 arrays?

• Separating data? You can separate using shares - you can even specify which shares uses which disk(s).
  
• Having 2 parity disks? You can have 2 parities with 6.2RC
  

Don't get me wrong, there are some valid use cases for needing 2 arrays; however, I haven't read anything on the forum that would clearly favour having 2 arrays i.e. the benefit is debatable and/or something else is way more suitable.

 

For your case, the simplest solution is probably to simply mix all together and having a 1x4TB disk as parity for 28TB usable or 2x4TB parity (for protection against 2 simultaneous drive failure - NOT to have an 8TB parity) for 24TB usable.

 

One very important thing to add is any disk you add to the array will be fully erased (unless the disk has already been used in another unRAID array but that is probably not applicable to your case) - so be careful with the 4x3TB that already has data.

You might want to start with the (presumably) empty 4x2TB + 2x4TB (note: don't add parity yet) -> copy the data over from the 4x3TB -> double check the data is ok (e.g. checksum and no SMART error) -> add parity and build -> clear the 4x3TB -> add 4x3TB -> redistribute data manually if desired.