ZFS Pool status understanding

[rahulku]

Hello. I am new to ZFS. I am trying to understand what the following output is telling me. I think I have figured out that the last disk is not part of the raid. I added it in later.

How can I get more information? Is it possible to take the last disk and make it part of the raidz1?

Code:

  pool: tank
  state: ONLINE
  scan: scrub canceled on Sun Nov 13 06:31:39 2022
config:
        NAME                                            STATE     READ WRITE CKSUM
        tank                                            ONLINE       0     0     0
          raidz1-0                                      ONLINE       0     0     0
            usb-WD_easystore_264D_4341303248544D4B-0:0  ONLINE       0     0     0
            usb-WD_easystore_264D_4341304B424C324B-0:0  ONLINE       0     0     0
            usb-WD_easystore_264D_4341304B3935344B-0:0  ONLINE       0     0     0
          usb-WD_My_Book_25EE_3753483936324143-0:0      ONLINE       0     0     0
errors: No known data errors

 

[jgreco]

Hello. I am new to ZFS. I am trying to understand what the following output is telling me. I think I have figured out that the last disk is not part of the raid. I added it in later.

How can I get more information? Is it possible to take the last disk and make it part of the raidz1?

Run, don't walk, run over and read

Why you should avoid USB attached drives for data pool disks

This subject has been coming up quite often since about 2022. Perhaps because of TrueNAS SCALE has brought forth some attention to TrueNAS in general and ZFS in specific. Please note that this is about USB attached storage for ZFS data pools. On occasion, people use USB drives, (flash...

www.truenas.com

 

[rahulku]

thanks for the link. I appreciate that. It still does not answer my question as to how i can get more information about that last disk. i cannot remove it since offline says "no valid replicas".

i am trying to understand what/how that disk is being used in the pool.

 

[Ericloewe]

It's its own vdev. If that disk fails, your pool fails.

I added it in later.

Yeah, that's a problem, because you can't do what you presumably wanted to do. You can't undo what you did, either. And you ignored the warnings TrueNAS gave you when you tried to do this.

You should probably read this ASAP: https://www.truenas.com/community/resources/introduction-to-zfs.111/

And now you have two solutions:

1. Destroy the pool and redo everything
2. Add a mirror to the single disk

 

[rahulku]

It's its own vdev. If that disk fails, your pool fails.

Yeah, that's a problem, because you can't do what you presumably wanted to do. You can't undo what you did, either. And you ignored the warnings TrueNAS gave you when you tried to do this.

You should probably read this ASAP: https://www.truenas.com/community/resources/introduction-to-zfs.111/

And now you have two solutions:

1. Destroy the pool and redo everything
2. Add a mirror to the single disk

Thank you so much. My goal is to add two more disks. I will end up with 6 total. But, i want them to be part of the same raid. Is that possible?

 

[Ericloewe]

But, i want them to be part of the same raid. Is that possible?

As I said above, no (not yet - the PR has been quite an odyssey). You would have to redo it all from scratch.

 

[rahulku]

As I said above, no (not yet - the PR has been quite an odyssey). You would have to redo it all from scratch.

Thank you very much. Truly appreciate the interaction.

I think I will have to get another disk then to ensure that I am not at a single point of failure at this point. If I get one more disk what is a good way to add it to my current setup?

i have data that I do not wish to compromise on my current setup.

 

[spuky]

I think I will have to get another disk then to ensure that I am not at a single point of failure at this point. If I get one more disk what is a good way to add it to my current setup?

2. Add a mirror to the single disk

you add it as a mirror to the one disk...
then you will have a mirror and a raid-z1 vdev...

in the long run backup and rebuilding may be the way to go.. but read up on ZFS before putting you in a bad position again...

 

[Ericloewe]

Well, first of all, all the USB-attached disks are not great for reliability.

That said, independently of how the disks are connected, you will want to add the disk as a mirror to the vdev that's just a single disk, as per the manual:

Pool Screens

Describes the fields on the Storage Pools screen on TrueNAS CORE.

www.truenas.com

The manual has a brainfart. Where it says "Each Dataset has two options available from the [hamburger menu]" it should read "Each vdev has two...".

 

[rahulku]

Thank you everyone. I will embark on creating redundancy and then on creating a better raidz pool in a bit when I can get more disks.