Logical drive bigger than 2 TB

  • Last Post 26 October 2017
  • Topic Is Solved
Tom Wootton posted this 17 October 2017

I have a logical drive that is 6 TB so I know it must be possible, but I cannot seem to make a raid 5 drive bigger than 2 TB on my iMac using either OS 10.12 or OS 10.13. I have 3.99 TB available when setting it for raid 5 but it tells me there is not enough space to make the logic drive. If I make it 2 TB I can make a 1.99 TB drive after that so the space is there. What can I do to make a 3.99 TB logical drive instead of 2 and 1.99?

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Pradeep Chidambaranath posted this 17 October 2017

Hi Tom,

Please go to https://support.promise.com and register the product and create a support case for further investigation.


Pradeep C

Raghuraman Kannan posted this 17 October 2017

Hi Tom,

We need few details to help you further with your query.

- What is the Pegasus Model number (4bay or 6bay unit)?

- What is the current individual drive size used in it ?

- We will be able to create multiple logical drives using the Promise Utility . Please let us know if there is any data in the unit.

Thanks !

Tom Wootton posted this 17 October 2017

Promise 2 6 Bay 3 TB each

current logical drives: 1 TB, 1 TB, 2 TB empty, 1.99 TB empty, 6 TB - all but those marked empty have a lot on them.

I can delete the 2 empty ones and want to do that to create a singly 3.99 TB one.



R P posted this 18 October 2017

Hi Tom,

In order to create a new logical drive from the space occuppied by deleted logical drives, the logical drives deleted must be contiguous, that is, they must be next to each other. You can tell because the LD numbers will differ by 1.

It is not clear from the above how the LDs are aligned. If they are in the order you present them above...

LD0 - 1TB

LD1 - 1TB

LD2 - 2TB

LD3 - 1.99 TB

To get 3.99 TB you'd have to use the space occuppied by LD3 and LD0 (not contiguous) or LD3 and LD1 (also not contiguous), neither can be done. Given your original post it would look like the LUNs are not contiguous so their space cannot be combined.




Tom Wootton posted this 19 October 2017

Thanks for the info Richard. I think since I added and subtracted logical drives a few times it is likely that even though the two are currently showing up as contiguous that you have identified the problem. I have some cleaning up and backing up to do but am planning on deleting all but the 6 TB LD and starting over with the largest drives first.

Thanks again for showing me what I hope is the solution.

R P posted this 19 October 2017

Hi Tom,

I was assuming that the 6TB LD is the last LD, if that is true, after deleting lower LDs you should be able to make an LD as large as the empty space. If the 6TB LD is not the last LD, then this will change.

But backing up important files is always a good idea.




Tom Wootton posted this 26 October 2017

Thank you to everyone, especially Richard, for helping me resolve this problem. After backign everything up to otehr drives I deleted all logical drives except one that is 6 TB. I then tried to create a new logical drive that is anther 6 TB and it did not work. That made me think that maybe the one I kept is not at the beginning or end so there is space on both sides.

I then tried 5.9, 5.8, etc. until I had success with 4.0 TB. I made a logical drive that size and then tried one with the remaining 1.99 TB which accoutns for all of the space avaialbe. It worked, so I deleted it and made it into two logical drives for my needs. It woked out OK thanks to the help I got here. I could have made to 6TB drives by deletignhte existing 6TB and startign over, but since I actually wanted a 4TB and two 1 TB drives it worked out.

Thanks again for the help. I shared my solution in hopes that it might helps somenone else who runs into a similar problem.