Migrating data to another pool

TrueNAS General
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1

Hi
I’m planning to migrate my 6 wide, 2 x RAIDZ2
To 4 wide, and 3 x RAIDZ2

Truenas Scale ElectricEel-24.10.0.2

Since i have no more slot for new disk, is it ok to do these steps?

  • Put 2 disk from each VDEV as Offline
  • Pullout disk and replace with new high capacity disk.
  • Create new pool from those 4 new disk.
  • Migrate important data to new pool (apps & user dataset)
  • Delete old pool
  • Add old disk to new pool VDEV in fours

Need some assistance to verify my steps if this are applicable and wise for pool migration. Please add if there Is any other steps i might missed.

Much obliged
software70

2

Can you please provide details of your existing disks and the 4 new disks i.e. the exact model numbers?

3

Current pool consist of 6tb and 4tb disks vdev

Device Model: WDC WD60EFRX-68L0BN1
Device Model: ST6000NM0115-1YZ110
Device Model: ST6000NM0115-1YZ110
Device Model: ST6000NM0044
Device Model: ST6000NM0024-1HT17Z
Device Model: ST6000NM0024-1HT17Z

Device Model: ST4000NM0033-9ZM170
Device Model: ST4000NM0033-9ZM170
Device Model: HGST HUS724040ALA640
Device Model: HGST HUS724040ALA640
Device Model: HUS726040ALA610
Device Model: TOSHIBA HDWE140

And as im planning to move to 4 disk per vdev. my plan is to get 4x 12TB ST12000NM0127 disks.

Once apps and dataset migrated, the plan is to add those disk back as four disk vdev to the pool.

4

They are all Enterprise disks and so CMR.

The next question is why you want multiple vDevs rather than a single vDev per disk size?

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5

Initially i start with 6x 6tb 1vdev.
As time goes by, i need more capacity and i have lots of 4tb disk laying around. So i added 2nd vdev with 6x 4tb disks.

And now looks like i need more capacity, but large sized disk is expensive if i want to add 6unit in one go.
I see its more cost efficient for me to only get 4. Thus the decision to move to 4 wide vdev.

6

OR in ElectricEel you can simply add a single drive to an existing RAIDZ vDev!!!

I am NOT suggesting that you rebuild your pool just to have wider vDevs, but you can expand your existing vDevs rather than add a new one, and if you are rebuilding anyway then you should use wide vDevs when you do so.

1 Like
7

But yes, you can make a pool with removed drives, and you can then add additional vdevs.

I personally wouldn’t use 4-way RaidZ2. I regard 6-way as a sweet spot.

For perf reasons I’d use mirrors in a 50% redundancy scenario. Mirrors have so many benefits.