Is there a way to control which disks in a pool are to be used for duplication?

[jonomite]

I have a large external hard drive that I'd like to use purely for duplicating certain folders from my DrivePool. Is there a way to control this? Ideally, since it's external, I'd like to be able to remove the drive when it's not needed (e.g., when I'm not copying files to the pool). 

[Umfriend]

You could use Hierarchical Pools. Say you have disks A, B internal and C is the external one. You can then:
1. Create a Pool Q consisting of A and B, no duplication
2. Create a Pool R consisting of C, no duplication (*)
3. Create a Pool P consisting of Pools Q and R, x2 duplication.

However, I don't think there is a good way to deal with temporarily removing drives. AFAIK, if you then (physically) remove/disconnect drive C, DP will put Pool P in read-only mode. May be what you are looking for but I'm not sure that will always work out well. Moreover, is that a USB connected drive? AFAIK, using USB-connected drives is not considered best practice and IIRC, it has led to problems, including data loss, due to connections over USB sometimes dropping for a bit (which I think is still within spec for USB).

(*) you could also create Pool P with Q and C, so without the intermediary step of Pool R but I think it makes it a bit harder to manage when removing/adding.replacing drives.

[jeffreybeach@gmail.com]

On 1/12/2020 at 4:26 AM, Umfriend said:

You could use Hierarchical Pools. Say you have disks A, B internal and C is the external one. You can then:
1. Create a Pool Q consisting of A and B, no duplication
2. Create a Pool R consisting of C, no duplication (*)
3. Create a Pool P consisting of Pools Q and R, x2 duplication.

However, I don't think there is a good way to deal with temporarily removing drives. AFAIK, if you then (physically) remove/disconnect drive C, DP will put Pool P in read-only mode. May be what you are looking for but I'm not sure that will always work out well. Moreover, is that a USB connected drive? AFAIK, using USB-connected drives is not considered best practice and IIRC, it has led to problems, including data loss, due to connections over USB sometimes dropping for a bit (which I think is still within spec for USB).

(*) you could also create Pool P with Q and C, so without the intermediary step of Pool R but I think it makes it a bit harder to manage when removing/adding.replacing drives.

Umfriend, I'm try to do something similar just with a 4 bay DAS. I have 4 - 12TB drives. A, B, C and D. I want A and B pooled no duplication and C and B pooled no duplication aswell. But I want C and D be a duplication of A and B so I have a better idea what drives are doing what.

So I think I need to create pool E = A + B no duplication and F = C + D no duplication.

Then create pool G = E + F with duplication.

So if above is correct then which pool do I want to write to? My guess is write my files to pool G or maybe E?. If that's correct then can I hide the other pools somehow so I see only the pool I need to write to. 

 

Thanks in advance 

[Umfriend]

Ah, you would write files to G:\. DP will save two duplicates to E and F. Each of E and F would divide single instances to A+B and C+D respectively.

Do not write to E or F. You can, but those files will only be part of Pool E (or F) and not be duplicated. Much like writing to a drive directly outside of the hidden PoolPart.* folders, those would not be part of any Pool.

[jeffreybeach@gmail.com]

On 3/4/2020 at 11:16 AM, Umfriend said:

Ah, you would write files to G:\. DP will save two duplicates to E and F. Each of E and F would divide single instances to A+B and C+D respectively.

Do not write to E or F. You can, but those files will only be part of Pool E (or F) and not be duplicated. Much like writing to a drive directly outside of the hidden PoolPart.* folders, those would not be part of any Pool.

Thank you for the help, I have it all set up and working perfectly.