I own a HP Proliant Micro Server Gen10.

And it run FreeNAS.

I put at the not deliverd CD device, a 250GB SSD for the system and 4 disks for the data. 2×3TB and 2×2TB. Perfect to make two differents zpool.

On day I decided to change the both 3TB disks by 2 6TB disks. Here is how-to make this change.


In addition of the server and the disks I used a double devices dock station.

The process

This process cannot by made with the FreeNAS web interface. It’s better to use a ssh connexion of the shell acces from the admin tool of the FreeNAS interface.

Attach the new disks

Once the dock station is plug-in with the two disks, we use the command dmesg to see them a have the devices names 1:

Extract of the dmesg command

As you can see our new disks are in da0 and da1.

Where gonna to make a 4 faces mirror.

The zpool status Pool give use information about the existing mirror: The command zpoo status Pool

The gptid/<dummy_characters> will be useful for the next step.

To add our new disks to the pool we use those commands:

zfs attach Pool gptid/<dummy_characters> /dev/da0
zfs attach Pool gptid/<dummy_characters> /dev/da1

As we can see on the next image, the resilver process start. In fact it copy the data from the 2 firsts disk of the mirroir to the 2 new disks:

resilver in progress

  This step could take a long time, be patient.

Once the reliver process is finished we can go to the next step.

Detach the old disks

We gonna use the FreeNAS we interface in order to detech the old disk form the mirror.2

On the storage part, click on the gear icon (⚙) the have a contextual menu and choose status.

At the end of each old disks of the mirror, click on the three verital dot (⋮) in order to have another contextual menu and choose Detach. There is no risk, the new disks are in the mirror.

Removing the old disk

Once the old disk are not even part of the mirror, stop the server, and swap the new disks form the dock to the place of the old disks in the server. You can safelly restart the server, ZFS will find all the piece of the mirror.

To conclude

This manipulation is easy but must be made with method. You can make it with a one device only dock station, but it will be more difficult and take more time.

I recycled the old 3TB disks and replace the 2TB disks by them, using the same method.

  1. Like you I did not like images for commands lines output. But there is not copy/paste to do and I did not think avout this article when I made this intervention. ↩︎

  2. We use the FreeNAS web interface because FreeNAS use an internal database. It will be very dommageble to have a garbage database. ↩︎

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