Truenas Scale install on emmc drive in UGREEN DXP2800

TrueNAS General
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Hello,
I’m new to TrueNAS and wanted to start with a UGREEN DXP2800 with 2xNVME, 2x3.5" hdd, 1x eMMc, 32GB DDR5 (hopefully).

First installed on the mirrored NVME-drives but found that I could not use them for anything other than the OS. So, thats a waste of 2x 4TB NVME.

Therefore my question:
Can I install TrueNAS on the internal eMMC card and redirect all the heavy writing (logs etc.) to the NVMEs so the eMMC will not exhaust within a day or so?
How would I do that or where could I dead that up?

Other alternative would be to install Proxmox on the NVMEs and TrueNAS in a VM sitting on the NVMEs and passing it the SATA controller to use the two SATA disks. Downside is TrueNAS would loose acess to the NVMEs.

What would you recommend?
Thanks a lot and regards from Munich
Claus

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I meant ‘read’ that up, sorry

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You cannot redirect boot drive writes elsewhere.

My understanding is that an eMMC is a small SSD on a chip that is soldered onto the MB. (I ran Windows off one of these for years and it didn’t fail - so I assume it is NOT the equivalent of a flash stick with low TBW.)

32GB is just fine for a TrueNAS Scale boot drive - so assuming it has SSD lifetime TBW, I would install TrueNAS on this eMMC.

Use the 2x NVMe drives as a mirrored apps pool to store VMs and apps and their data.

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ok, thank you, that’s unfortunate.
Since I don’t know the quality and TBW capacity of the eMMC drive used in the DPX2800, I am a bit reluctant to using it as a TrueNAS boot drive.

Is there a way to reduce the write load of the boot drive?

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You can (assuming the hardware allows) boot off a USB drive - but not a thumb drive [well you can, but its ill-advised]

Use a USB to SATA or USB to NVMe bridge and then use a proper small SATA SSD or NVMe. Nothing bigger than 32GB is required (and you can get away with less, minimum is 8GB, but sensible is 16GB)

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My NAS uses a USB SSD as a boot drive - and I can say from experience that it is less reliable than a SATA drive, and the reliability can be dependent on the type of USB port it is plugged into. My DOM SATA port is unreliable, an external USB is more reliable but not completely reliable.

My advice is NOT to use a USB drive for boot if you have sufficient NVMe or SATA ports to avoid it.

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Thanks all for your help, I think I will go with a small internal NVME in one of the slots, thus I have one large NVME and two SATA hdds left for data / vms.

I am not especially fond of a USB ssd dangling from the front USB port (the rear ports are all 5 Gb/s only).

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You can use a USB2.0 to boot from. Its a boot disk - doesn’t need to be fast

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This is true - you can use a USB2 and it doesn’t need to be fast, but it is still not a good idea unless you absolutely have to.

NVME for an apps pool to hold VMs and apps and their active data, and backed up through replication to the HDDs.

HDDs for at-rest data - media files, backups etc.

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that would probably be the best approach. Thanks and best regards from Munich, Claus

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you can move the “System Dataset” onto another pool, which should alleviate a lot of the writes to the boot-pool…

also, you can mirror the boot-pool, two flash drives will be more reliable than one! You could also do something like mirror the eMMC and a USB flash drive together for some level of cheap redundancy. (you can mirror it after install, too)

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Mirroring the eMMC is an interesting idea. Since it is soldered onto the board I’d have to deactivate it once it fails but in this case I would still have the mirror which I probably could mirror against another flash drive later. Thanks for the hint.

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eMMC drives may be NAND but they are typically designed to hold an O/S which has writes. More like a SSD than a flash stick.

You can use a flash stick as a mirror, but why not get a USB SSD stick instead and save the hassle of your flash stick failing every few months.

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I have two identical ‘old’ Crucial MX500 m.2 SATA drives laying around. Initially I didn’t want to use an external ssd but I will probably use those anyway.
One advantage is that I can easily backup / clone them without having to open the case of the DXP2800.
So I’m going that route, thank you all for your help.
Best regards from Munich, Claus

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So what is your final solution? I myself disabled the emmc and installed TrueNas Scale on a 1TB NVMe Drive with partitions of 16GB the rest of the NVMe Drive is used for/as application store.

I have still a slot avail and wonder if i can mirror this to another 1TB NVME Drive

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Not sure why you referred to random characters in one of my previous posts, however…

I am not sure what happens if you mirror the boot drive to another NVMe card, but I suspect that TrueNAS will only mirror the boot pool and boot - and when you do this it may create a full disk partition to mirror it to, in the incorrect assumption that you will later want to replace the “smaller” NVMe boot drive with a new “bigger” one.

Mirroring the boot pool using the CLI probably won’t do what is needed to mirror the Grub etc. configuration.

So my guess is that mirroring the drive containing both the boot pool + apps pool on the same NVMe may be problematical.

Because sharing a boot drive with other pools is outside support, you might actually be better off buying a small NVMe for your boot pool and converting your 1TB NVMe to a pure apps-pool, and instead of mirroring the apps-pool you can replicate it to HDD as a backup.

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