Missing Space on Raid 5

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Missing Space on Raid 5

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I have a DS918+ with a DX517 Expansion box.
I set the Raid as Raid 5 , 2 data drives and 1 checksum drive , using the drives from Western Digital 8tb Drives USB drives

The DSM , reported I was at 72% drive usage with 9.42Tb Drives Space.

The recent Amazon Black Friday had the Western Digital 8TB Drives at £129 so I bought three and fitted them.
It took about a week for the DSM to prep them but when it had finished , instead of the extra 16tb Expected , i was left with 72% drive usage with 9.42Tb Drives Space.

Using the Drive Storage Manager i can't find where it has gone wrong . or even what each drive is assigned as

I would like to get back the 16tb missing !!!!!

thanks in Advance


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Reading this you started with RAID5 using 3 drives. Then you got 3 more, but I see a single volume with 9 drives. So what happened with 3 more drives?

In any event, the expansion of the pool should be followed automatically with the expansion of volume (considering the pool is using a single volume).

What options do you have under the Volume > Action menu? Is there a Configure button? What options do you have there under max capacity?
Expanding a volume using an expansion chassis has the potential for data loss if the cable connection fails, better to put the drives in the Expansion chassis into a separate volume then it can recover if the plug drops out.

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