What are you going to use it for?/How important is the data?
Do you have backups of the data for when it fails?
I’ll add that for a system with so few drives, you have a very powerful CPU that isn’t going to see much use most of the time.
What are you installing the OS on? The 990 Pro 1TB? If so you’re not going to be able to use that drive for anything else so it seems like a waste of money. If you intend to use it for VMs/Apps get another small SSD and install the OS on that instead.
Without knowing your use case, and overall backup plan, the key point is that mirrors are flexible, but relatively expensive (50% space efficiency at best), while raidz is more efficient; while you can now expand raidz vdevs, you cannot change raidz level—so if you plan to enlarge your array, you’d better start with a higher redundancy level.
I currently have a Western Digital NAS “My Cloud Pro Series PR2100 - 2 TB” with 2 WD Gold 2TB mirrored HDs but the space is no longer enough. My Cloud Pro Series PR2100 - 2 TB
I currently have a total amount of data that is close to 2Tb for my users
I currently use “Iperius backup” software to perform data backups. https://www.iperiusbackup.it/
I wanted to upgrade to something more professional for my office and my users.
The use is corporate 15 users.
For now I have installed the truenas scale operating system on the Samusung SSD M2 1TB unit while waiting to decide on the HD to use and the type of RaidZ.
You should use HDDs in RAIDZ for at-rest, mostly inactive, mostly sequentially accessed data (backups, media files etc), and mirrored SSDs for active or randomly accessed data (zVolumes/apps and their data, databases etc.). You will also need a small (32GB is what you actually need) SSD for a boot drive.
It is your choice about whether to use 3x 12TB RAIDZ1 or 4x 12TB RAIDZ2 - it depends on your risk profile. All I can say is that I have a 5x 4TB RAIDZ1 and I wish I had built it as 5x 4TB RAIDZ2 instead, and that for a commercial multi-user environment like yours I wouldn’t think twice about doing RAIDZ2. I would also think about using a 3x mirror for the SSDs, but due to hardware constraints you may want to do a 2x mirror and replicate it to HDD as a 3rd copy.
For this config, I would probably buy one or two small SATA SSDs for boot and 2 more 1TB Samsung M.2 for a mirrored SSD pool.
Remember to define short and long SMART tests for each drive, scrubs for each pool, and snapshots for each dataset. And I also recommend that you implement @joeschmuck’s Multi Report script. And as @neofusion pointed out, also remember that redundancy and snapshots are NOT the same as remote or offsite backups for your critical data.
For a commercial multi-user environment, ECC memory is a good idea IMO.
For offsite backups, there is too much unknown to be able to comment, however TrueNAS Scale has support for various 3rd party services, but for a commercial environment I would try to find one that allows you to do ZFS replication at reasonable cost (because you will probably want to replicate everything and ZFS replication will be the most efficient).
IMHO 32gb Is more than enough.
But i understand will be hard found new small disks at a reasonable price… In case evaluate second hand you probably achieve a good disk for 5/10€.
Last day my boot pool die, i just slap in the first SSD laying around at home, waiting a 16gb optane NVME come (less than 5€). Last config provided by multi report, fresh install and back online literally in 15 minutes… Just for Say that boot pool Is not so critical to spent 30-40€ on it
Multi-Report does not work in TrueNAS 24.10.1. The community is trying to solve a newly implemented “feature” in 24.10.1 and it is unfortunately not solved yet. I am working on a temporary fix that I hope is actually temporary.
I see something for less than 15€ on Amazon, we are talking about lesser-known brands disks… But for the boot pool they still will be good.
Your call, off course… Just remember that space on boot pool can’t be used for anything else ( and seeing the data write on mine, don’t think neither the tbw of smaller disks can be a concern)
I opted for a single disk, because im not concerned about eventually downtime if the boot pool fail (Is just an home system), i can easy access the Nas for a disk replacement, and honestly instead of consume a disk for this job i pref keep one more ready to use in case of need (like i have done ).
What Is really important Is have a recent config backup file