RaidZ2 on partitions

[Omega Destroyer]

I'm considering moving from Windows Storage spaces (which I've actually been quite happy with and successfully replaced failed drives a couple of times) to TrueNAS.

I have 4 x 10TB and 4 x 12TB drives that I want to put in RaidZ2. Naturally, the TrueNAS GUI takes the whole disk, but given the matching requirements, that leaves 2TB of each 12TB disk that goes unused.

Now I could just live with it, but given that one of the benefits of software RAID is flexibility, and various forums posts about pools running fine on partitions, I would like to use the remaining 8TB in some other pool (different configuration).

I understand the performance implications of using the same physical disk in different pools, but there will rarely be cases where files are read or written to the two different pools, I am willing to make that trade off.

I found several posts about people partitioning SSDs for ZIL or L2ARC, but that's not what I'm doing here. I would like to use the remaining space on drives in the pool to create another pool.

I've currently playing with TrueNAS is a Proxmox VM with some fake virtual disks to try various configurations before migrating my data. I want to simulate disk failures, different setups etc so I feel confident I can deal with things before I make the transition. If I partition the virtual disks with Gparted (live CD), then boot into TrueNAS, TrueNAS doesn't even see the disks anymore.

Question: How would I partition the disks with GParted GUI and then boot into TrueNAS so it sees the partitions?

Caveat: I'm a Linux Noob (hence the reliance on Storage Spaces up to this point).

 

[Ericloewe]

Do you need the 8 TB now? You're making something that needs more manual twiddling of knobs for both setup and disk replacement, for little gain. If the 10 TB disks get replaced with 12 TB or larger disks soonish, just wait it out and the pool will grow then.

Question: How would I partition the disks with GParted GUI and then boot into TrueNAS so it sees the partitions?

Copy the partition layout from an example disk (real or virtual), taking into account the extra size. There's not much more to it.
You will have to manually create the pool, however, as TrueNAS will want the whole disk.

 

[jgreco]

I'm just going to ask this question in hopes that it frames your question in a less optimistic way, which could in turn prevent you from making a terrible mistake.

If you have to ask this question, how do you expect to be able to recover when one of your disks fails and you suddenly have to re-engineer this ill-advised solution? You can absolutely do this, though you'll break things such as TrueNAS-driven disk replacement. One of the reasons to avoid looking at NAS as a "software problem" and instead attempt to work within the appliance design is because you don't really want to be on your own when resolving issues during a crisis.

 

[Omega Destroyer]

Thank you both for the replies. I don't absolutely need the extra 8TB, but that being said, it's not a trivial amount of space given my home setup.

I don't want to create huge problems and hoop jumping in the future to recover disks, but I feel like the appliance itself should have the flexibility in the GUI so something like this is more simple to do. One of the benefits of Storage Spaces is the ease of use and from a technical perspective, the setup I'm proposing is not super out in left field.

I don't know how it's currently implemented, but in a ideal world, if a disk fails in this setup, you would replace it with a disk of equivalent size and resilver one pool then the other.

 

[Davvo]

Please just no.

 

[jgreco]

but I feel like the appliance itself should have the flexibility in the GUI so something like this is more simple to do.

You're welcome to feel like that, but it is very hard to do in a portable, automatable manner so that this can work reliably. When Sun Microsystems designed ZFS, they expected that it would be used on servers that had a dozen, or dozens, of disks sold as shelves, and they designed it accordingly. Trying to squeeze the maximum amount of space out of randomly sized drives was not anywhere on the design plans back in the day. It is not going to change now that the design has been here for 17 years. ZFS is not the right choice for everyone, and perhaps something like Unraid is more appropriate for your needs.

 

[Omega Destroyer]

@jgreco @Ericloewe First off, thank you both for your contributions to the community. In the numerous threads and questions I've been researching for the past two weeks to decide whether to migrate to TrueNAS, the two of you (plus a few others) were almost consistently there providing support for everyone. I admire your dedication to the software and helping others.

ZFS is not the right choice for everyone, and perhaps something like Unraid is more appropriate for your needs.

I think this statement captures exactly the conclusion that I'm coming to. TrueNAS is great at what it does (arguably the best), but perhaps for the average home user, it's limited feature set might not be the right fit. For example, not being able to add disks to existing vdevs or doing things like I mentioned in the original question.

Being around for 17 years means it's super robust and tested and for data security that is absolutely essential. But, maybe that's also one of its weak points, because other software raid options have come along with more advanced features and TrueNAS has not evolved as quickly.

Maybe the code base makes these kinds of changes difficult or next to impossible, but when the code was originally being written and people were migrating from hardware raid, the flexibility it offered was really useful, but the whole field has evolved so much in the last decade.

Again, I really wanted to move to TrueNAS, but I realize that it's not a magic solution for all use cases.

Thanks again for supporting myself and the community!

 

[Arwen]

To come from another direction than @jgreco, iXSystems is making Enterprise NAS appliances which are engineered for higher than average reliability. Thus, the design of TrueNAS does not support such a configuration in the GUI.


That said, I DO use partitions with ZFS for my home Linux computers. One partition from each device for the boot pool mirror and the other partition for general storage pool. However, I have to manually manage it. For someone who literally says they are a Linux Noob, this would be a bit difficult. And recovery could be enough worse.

 

[ChrisRJ]

I'm considering moving from Windows Storage spaces (which I've actually been quite happy with and successfully replaced failed drives a couple of times) to TrueNAS.

Irrespective of the direction this thread has taken, the very first thing is to be clear about motivation. If you are happy with the existing solution, why change? Wanting to learn new stuff is a perfect reason, and was certainly my motivation over the decades. Whatever it may be, being able to answer that question will be the best guidance.