Upgrading Capacity/Migrating Pools

[Leharris97]

Hey all,

Im looking at upgrading my pool to a higher capacity storage. Currently have 5x 2TB drives and have picked up 3x 6TB drives. I saw that I could swap out the 2TB drives one by one and then once they have all been swapped the pool would upgrade itself to the higher capacity but I was only planning on putting the 3x drives in at the moment. 

Would the best way to go about it to be create a 2nd pool, copy everything over and rename the pool once the original pool has been removed?

Thanks

[PsychoWards]

Hey, this depends on a couple of things. Do you have any apps installed? If yes, I'm not sure how this is going to look like after the migration to another pool.

Also, do you have enough slots to connect all the drives at the same time? 

If yes, creating a new pool will be the only way to get more storage with your current number of drives. Once the new pool is create, you need to login into Truenas and use the task replication to copy everything over to your new pool. This is the best and safest way to copy things over to the new pool. 

[Mobius]

14 hours ago, Leharris97 said:

I saw that I could swap out the 2TB drives one by one and then once they have all been swapped the pool would upgrade itself to the higher capacity but I was only planning on putting the 3x drives in at the moment. 

this method likely wouldn't work well for you because your original pool is only 2 drives. Expandable pools require to originally made with 3 or more drives.

@PsychoWards's solution is likely the best, plug them all in at the same time and then copy over your data.

 

[eldcmx]

On 2/25/2026 at 1:50 AM, Mobius said:

this method likely wouldn't work well for you because your original pool is only 2 drives. Expandable pools require to originally made with 3 or more drives.

@PsychoWards's solution is likely the best, plug them all in at the same time and then copy over your data.

 

Hi, 

I’m trying to upgrade a 2 drive pool to a 3 drives pools but with a twist 

I can only plug 4 HDDs at once in my motherboard

And I have a bunch of apps running

how would you proceed? 
(TBH it’s mostly Linux iso and a game library so losing it is not such a big worry but I’d rather not have to redownload the whole thing)

[PsychoWards]

Hey, 

So, the save approach would be to get an HBA card so that you can connect all 5 drives together and copy your data using the task replication in the Truena GUI. You can use the HBA in future if you want to add more then 4 drives to your pool or if you want to create a 2nd pool. 

However, if you don't want to buy a HBA card, you could, although I strongly advise against it, unplug 1 drive from your current pool, plug in the 3 other drives, create your new RaidZ1 pool and copy the data over this way, again using the Truenas replication task.