How to replace boot pool disk correctly in 13.3u1.1

TrueNAS General
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1

Hello,
I upgraded from 13.0u6.2 to 13.0u6.7 to 13.3u1.1 and everything is running without a problem. After the installation I got the error message that the boot pool was degraded. These are two (by now older) 32GB USB sticks, one of them has failed.

$ zpool status freenas-boot
  pool: freenas-boot
 state: DEGRADED
status: One or more devices could not be opened.  Sufficient replicas exist for
        the pool to continue functioning in a degraded state.
action: Attach the missing device and online it using 'zpool online'.
   see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-2Q
  scan: scrub repaired 0B in 00:09:00 with 0 errors on Mon Apr 14 03:54:00 2025
config:

        NAME                                            STATE     READ WRITE CKSUM
        freenas-boot                                    DEGRADED     0     0     0
          mirror-0                                      DEGRADED     0     0     0
            gptid/dfe4fb42-75b5-11e5-9e2e-d8d385636e4c  UNAVAIL      0     0     0  cannot open
            gptid/e008ef26-75b5-11e5-9e2e-d8d385636e4c  ONLINE       0     0     0

errors: No known data errors
$ gpart show /dev/da0 ### NOTE: remaining functioning 32GB USB
=>      34  60062433  da0  GPT  (29G)
        34      1024    1  freebsd-boot  (512K)
      1058         6       - free -  (3.0K)
      1064  60061400    2  freebsd-zfs  (29G)
  60062464         3       - free -  (1.5K)

$ gpart show /dev/da1 ### NOTE: not partitioned yet...
=>        1  121307135  da1  MBR  (58G)
          1         31       - free -  (16K)
         32  121307104    1  ntfs  (58G)

I would like to replace the failed USB stick with another one that I have, a 64GB stick. How can I do this correctly, and ensure “bootability” from both USB sticks? The steps look to me like:

  • copy partition the new USB stick (clone the 32 GB one, and then expand the second partition to fill the stick?)
  • zpool replace

I’ve looked at the gpart partition cloning, but haven’t found anything that would essentially clone the bootability of the stick (and would ignore the last 32GB of the stick, which I could live with, but will probably replace the other stick too soon just in case).

Thanks for any thoughts / help.

2

How I would do it…

  1. Create a backup on your TrueNAS configuration file, very imporant step!
  2. Replace the mirrored boot-pool drive via the GUI. If you buggar that up, go to step 3.
  3. Or I would just install TrueNAS to the new USB drive and restore the config file.

You only need one boot drive, just ensure you maintain a backup of your config file.

I’m certain you have heard this before but USB Flash drives are not well suited for TrueNAS these days. If you must use a USB connection, the best small thing I have found is using a USB to NVMe m.2 adapter and a very small capacity NVMe module. You can use pretty much any USB hard drive, preferably not an Archive drive which is typically an SMR drive.

Good luck

2 Likes
3

Eh, that is generally not a real working thing unless you are lucky and the failed drive is completely not recognized by the BIOS. If the failed boot drive is corrupt, it could leave the system in a failed state and never move on to the other drive.

4

Thanks for the input. I hadn’t heard that USB is not to be used anymore… it used to be that the boot device was read from and then never used again. Now apparently it has swap? Is this true for the 13.3 CORE as well? I will probably stick to this solution for a few months, a rebuild of the system into an enclosure with more bays is pending and then I will go SSD for booting.

Re booting, I would want both to be able to boot so that if one fails completely or is unplugged, the machine boots from the other.

Managing the boot pool is not possible from the GUI apparently, I looked. See Boot pool doesn't appear in Storage / Disks | TrueNAS Community

I have the config backed up, so will try the replace and otherwise reinstall to a new USB.

5

This has applied to CORE for years. Get a cheap and small SSD, install anew and load the configuration file.

This will depend on how smart the BIOS is…

6

That hasn’t been the case for over ten years. With the release of FreeNAS 9.3 on 15 Feb 14, the boot device turned into a live ZFS pool. ZFS caching means that most of it lives in RAM most of the time, and not much is written to it in normal operation, but it definitely isn’t the RAMdisk that earlier versions used.

Sometimes–if it’s big enough and not USB.

Yes.

2 Likes
7

Thanks for the info and link. Will probably use USB for a while and rebuild the system. I currently have no internal space for more drives… may go the NVMe m.2 route.

Whats the state of current CORE / SCALE wrt ECC RAM? My current system has it. When I built that one there were religious wars over “absolutely must have else you will kill your pool” vs. “helpful but you will not lose data without it”

8

No different than it was ten years ago, with the obvious exception that SCALE didn’t exist then. It’s always a good idea on any system if you care about your data, but ZFS doesn’t require it any more than does any other filesystem.

1 Like
9

That’s a very good way to boot without losing a SATA port for HDDs. With an adapter, any PCIe x1 slot may be put to good use.
My go-to option for CORE is Optane M10 16 GB drives (go for 10€/$10 on eBay); for SCALE you may want to get a 100-120 GB drive to have a swap partition on it.