Modifying Volumes to optimize available space.

Its not so simple and no, it is not easy to do what you want. I think you need to keep the Drobo as secondary backup, btw.

(Always have 3 copies of data, it seems you had 1, now maybe two copies. Its not enough if this is precious data.)

You could create a second 40TB volume with SoftRAID (All partitions are equal in proper RAID 5), there will be 4TB left over.

The problem is expanding a volume, you can only move out, not in. So if you delete the existing volume, you cannot use that capacity to resize backwards, towards the beginnings of the disks.

Are you using RAID 0? Then your sizes make sense. If you are using RAID 5, you can create a 14 x 4=56TB volume max with 5 drives.

I have 3 copies of all my data on various Drobo not including a Synology DS1821 NAS.  As long as I can access the Drobo B810, there is no problem.  However all my Drobo are out of warrenty and Drobo is in bankruptcy.  No new ones are being made and used ones are at least 2-3 years old, also without warranty. MacOS is updating to Ventura and Drobo will not function in that environment.  My Thunderbay 8 is Raid 5.  For simplicity, I'm using the total volume of memory including Raided memory.  Total memory on the Thunderbay 8 is 92Tb (3x6 +3x14 + 2x16).  Because of the size limitation, the only volume on the raid is 48Tb( 6x8).  According to the  Volume creation in Softraid, I can create a Volume 2 with a max size of 32 Tb, since I do not want to utilize any memory from the 6 TB HDD.  Volume 2 would have enough memory to transfer the data currently on Volume 1.  I would then delete the data on volume 1 and then volume 1 itself.  At that point I should have data only on Volume 2 ( 3x14+2x16), utilizable as 4x14 (56TB) over 5 HDDs

If I understand what your saying, even if I delete Volume 1 on my Thunderbay 8, I cannot remove the 3, 6 TB drives.  I can only replace them with larger drives?  If I delete  Volume 1, none of the 6Tb drives are included in Volume 2.  Can I then remove them and Create a Volume 3 using the memory left over from the deleted volume 1(56Tb)? Then I can add 14 Tb drives as needed to expand volume 3, when needed. 

  As I understand it, I can have 2 or more volumes, each of which exist scattered across the same HDDs.  Are you saying that the Volumes cannot exist on the same drives together?  What is the purpose of being able to delete a volume if you cannot utilize that space for anything else other than a volume of the same size?  Sorry to be so basic, but that is how my mind works.  I break complex ideas down and then try to rebuild them so I have a better understanding of the limits.

Thanks for you help.  WMB

@wmb 

Here is a way to describe this. SoftRAID allows any number and type of volumes in any order. No issue there.

However you have a special case, where you want to resize a volume. The API call we can use in MacOS, only allows volumes to expand "outward", never inward. (Note: There is currently a bug in the XCode that is preventing us from resizing volumes at the moment, we are hoping to resolve that soon)

What your only option would be to do this on your SoftRAID Array is:
Create a second volume.
Copy all the data to it.
Delete volume 1
Create a new volume 1 with only the 14/16TB drives.
Copy the data to that.
Delete volume 2
Expand Volume 1 to fill the 14/16TB drives.

Painful in this scenario, I understand.

Else, wait until you get your additional large drives, then do this all at once.

That is exactly what I wanted to do but wanted to be sure there was not a problem I didn't understand that would invalidate my reasoning.  I should be able to expand Volume 1 as needed, correct?   

Also, if I delete Volume 1, could I rename volume 2 to volume 1?  That would eliminate the second data transfer and volume deletion.  Thanks again for all your help.

WMB

@wmb You can always rename volumes, yes.

Thanks for all your help!  I have my answers, just gotta start.  I'll re-open if I have difficulty.

WMB

Sorry, I'm back.

 Data transfer was fast from Vol 1 to Vol. 2.  I deleted Vol 1 and then renamed Vol 2 to Vol 1.  When I attempt to expand Vol 1 (old 2), I get a message reporting I can only expand to 32 TB which is the same as the current size even though I have 22 Tb uncommitted to any Volume.  I updated to SoftRaid 7.0, but I get the same message.  Any insights?

WMB

@wmb 

I thought I mentioned, that a bug in SoftRAID 6/7 prevents expanding. Do you have access to connect this to a Big Sur computer, so you can run 6.0.5? (or an older system). Let me know.

Yes.  i have a Macbook Pro running Big Sur 11.4.

I downloaded SoftRaid 6.0.5 to the Big Sur MacBook and connected to the Thunderbay without difficulty but I get the same message from soft raid that I cannot increase the size of the 32 TB volume.

WMB

@wmb 

Attach a tech support file from that System. I can look. (with the disks connected of course!)