I just started using TrueNAS and it seems it would be fun and also challenge setup everything according to my wishes.
I am currently wondering about my first parametrization. I have 3 x 6 TB Seagate Ironwolf as a RAIDZ1. I have M2 SSD Samsung 970 EVO 2 TB. I have 32 GB eMMC → Ugreen NAS DXP4800.
I want use … 32 GB eMMC → for TrueNAS OS 3 x 6 TB HDD → Main pool RAIDZ1 2 TB M2 SSD → Partially for all apps files and other system files which can be re-allocated to different disc than boot disc (eMMC in my case). And partially as a cache for my main pool lets say around 500 GB.
My question is … is it possible to make two purpose SSD? And make it sense? To understand … I want to use my current HW setup as efficiently as possible.
It is absoluetly possible in ZFS but not supported by TrueNAS and therefore not recommended.
The UI won’t offer you this as an option but you can partition the disk via CLI, create a pool with just one partition as a stripe data vdev and then add the other partition as cache to the RAIDZ1.
This might cause some weird pool layout reporting in the UI and is not supported.
However my (an others) rule of thumb is not to tell you how to do it. If you can work it out yourself and wish to take the risk then go ahead, its your hardware and your data.
On a related note - I wouldn’t bother anyhow. Cache (L2ARC) rarely does any good for the home user. It doesn’t work as most people think it does (I think that cache is an appalling name for it) and rarely achieves the imagined objective.
Also: if you use just one SSD for apps so on this won’t have any redundancy of course so keep that in mind and maybe replicate it to the RAIDZ1 (in addition to the other backup you have of the whole NAS of course ).
No worry I am amateur, so I take recommendations seriously. Thank you for pointing to my SSD. What I understood you recommend replication.
I have spare 2 TB WD Gold HDD. But I am assuming make RAID1 with this SSD is not a good idea and better is replication? For my it is fine that it is not “realtime backup”
You’re right, creating a mirror from an NVMe and an HDD would be a terrible idea.
I don’t think you’ll be using a whole lot of the 2TB ssd for apps and the system dataset so I wouldn’t use an extra HDD just to replicate the SSD - I think it won’t take that much space on the RAIDZ1 and if it does you can still add the 2TB drive later.
