I wasn’t aware of Roonlabs have a recommendation beyond a NUC with i7, even the nucleus+ is based on the same hardware. However, I don’t see how number of tracks has to do with Processor requirement, probably need more memory and storage.
So what would be the recommendation for a huge library?
I have disabled background audio analysis and see if it can finish today. Or else I would need a few more days for my evaluation.
Question, If I start my subscription and then switch to lifetime, would I get a credit towards the lifetime subscription?
Within the 30 day money back period, you could get a refund and then purchase lifetime.
Note lifetime cost will increase significantly next year to avoid this you need to purchase it before January 1st 2023 or whilst your Roon trial is still active.
Let me tag @accounts for you, they may be willing to grant you an extension on your trial.
On the ROCK page, there are two categories given. The larger one is:
ROCK For Large Libraries (12k+ albums) or DSP Use
We recommend the NUC11TNHi7 with 8GB RAM and 256GB M.2 SSD for large libraries (12k+ albums) or heavy DSP use.
It says “12+ albums”, but obviously the “plus” is not infinity. With 350K tracks, I’d guess something like 35K albums? That’s three times as much. And you have in 10i5, not an 11i7.
Beyond that, the following quote is from Roon Core and Remote specification recommendations. Yours is in the “largest libraries” category 
Largest Libraries
If you have over 250K+ tracks in your library, consider us impressed! You’re among the top .01% of Roon users, and you have a library most of us could only dream of.
With libraries this large, we expect the right hardware will work, but it’s definitely not something that we test with in-house. Your best bet will be to get a beefy Roon OS or Windows setup (we do not recommend standard Linux or macOS Cores for this) with a fast new CPU and plenty of RAM.
Probably your are right for playback and I would expect your setup to probably play fine when it is done with the ingestion.
However, Roon is not just a music player, it is a huge database. in particular with 350K tracks. Searching this database and more so finding and setting up all the cross links takes CPU. It’s a database theory problem and my math is weak, but if you have 35K nodes (albums) and each nodes has 10 connections (e.g., credit links) to other albums, the number of connections probably grows with some power function. In any case, lots. They all have to be looked up online, found, connected, and so on.
I am trying to ascertain the Roon core system requirement because I just purchased a NUC11i7 with 32GB of memory and 512GB of SSD to run Rock, which is the highest spec machine on the approved list of hardware. If that is not sufficient, I would like to know now and get something with a higher spec. However, Rock will not be recommended for it then, so what’s the option?
There are many threads about huge libraries. This may be an option:
This thread has lots of information:
In essence, if you are going toward these library sizes, for good performance you may have to set up a full-size machine with lots of CPU power and RAM, then install Roon Server on it.
It might have got stuck on a bad file, if the importer is still spinning on the top bar, try rebooting. If that doesn’t help, click the wheel and find/remove the file it’s stuck on. With huge libraries, it might help to import small sections at a time, depending how you’ve split it up into sub-folders. From the FAQ:
In rare cases, Roon encounters a file it thinks can be imported successfully, but it actually causes instability for the importing process. Generally, this happens with files that are particularly corrupt. If your importing process seems stuck, it’s often worth searching your music folder for files that are tiny, meaning less than 5kb.
If I’m reading the posts you referred to correctly, basically for “outliers” with huge library, ROCK is NOT recommended. Instead, we should run Windows and Roon server? Is there a more definitive answer?
It appears that Roon is still making progress importing as new album artworks keep being updated in the “Recent Activity”-“ADDED” window. Monitoring the system resources shows that it is using about 40% of CPU and some bursting of network activities. So it doesn’t seem to be stuck…yet.
From the 10th post of the second linked thread:
There are no hard and fast rules at this level, I think. Just experience reports. Get the fastest CPU you can afford and at least 16, I would say better 32 GB RAM or more. Since the above quote, some things have improved: Roon 2.0 has removed the performance limitations on macOS, however, fast Mac servers are very expensive. Windows makes sense if you are familiar with it, though some people, at least in their specific situations, reported better support with Linux, in case this is an option.
On the other hand, who knows, your NUC may work well enough once the painful ingestion is over.
ROCK is, as such, very good for the purpose and all performance is used for Roon, not for Windows background processes. The problem is that super fast NUCs don’t exist (as mentioned, maybe the SonicTransporter i9 is an option). However, this does not necessarily mean that ROCK cannot be installed on non-NUCs, there is just no guarantee. ROCK installs on non-supported hardware are called MOCK. There is a thread about it
Going through your linked thread, some people are reporting running Nucleus+ fine with 700K+ tracks, which I understand is essentially a NUC11i7 with ROCK.
I’m trying to avoid running Windows if possible, hence I’m sticking with the list of hardware recommendation of using ROCK. If ROCK is out of the question and Windows is required, then certainly there are much more powerful machines that can be had. I’m trying to clarify if Windows is a requirement for huge library, or ROCK can still support it.
See my additional edit in the last paragraph of the previous post regarding ROCK on other hardware.
Sure some people are indeed reporting success, but are they saying how long the initial ingestion took? I also wrote above,
The other people have an i7 too, I don’t know why you didn’t buy the fastest possible option for ROCK. NUC12 are now supported as well. Anyway, I am not saying it won’t work at all with yours, just that the import may be slow and the cause of your pain. And search performance might not be blazing, but maybe it’s good enough.
What I would do in your situation is, like @mikeb suggested above, not importing everything at once but in batches. Then wait until it has settled down, check that it works, and import the next batch.
Since we moved Roon to .NET 6.0, Linux is now our best performing platform.
I would use ROCK, and consider MOCK if you can’t get a NUC with the performance specs you are looking for.
I am first trying it on a NUCi5 and reporting the problems above. I have since ordered the highest recommended ROCK hardware (NUC11i7 with 32GB RAM), which I will receive today. If that is not good enough for my configuration, I can return it and order something different, and that is what I’m trying to clarify.
I didn’t see NUC12 on the list yet.
I see, makes sense then. After the inclusion of UEFI boot support in ROCK with the latest RoonOS update, they have expanded the list first to some NUC11 and then with additional models including NUC12 after Intel delivered them. This was ongoing recently and I guess you looked before the latest additions. Here is the list as of now:
NUC11TNHi3
NUC11TNHi5
NUC11TNHi7
NUC11PAHi3
NUC11PAHi5
NUC11PAHi7
NUC12WSHi3
NUC12WSHi5
NUC12WSHi7
Thanks for the clarification. Since ROCK is based on a linux kernel, I would assume the success in installing on MOCK will hinges on whether it contains all the drivers for the peripherals rather than the CPU itself, especially the network component. Does it support AMD CPU or the latest 12gen/13gen Intel CPU with small and big cores, where the task scheduler will need to be aware of how to assign to appropriate cores.
Yes, it’s all about drivers/peripherals for the most part. MOCK configurations are not supported by Roon Labs, and I don’t have a list of drivers that are known to work well. We don’t have the resources to maintain a Linux distro for all hardware combinations, so we restrict to NUCs to keep the field small enough to manage.
Your best bet is to look at other people who have MOCK installs and what hardware they have managed to get working.
As @Suedkiez mentions the fastest supported platform for Linux based Roon Core is the sonicTransporter i9
Thanks, @Carl, for explaining so clearly what are the options this time around 
@Joe_Lam, I’ve replied to the email you sent us yesterday
Thanks to everyone’s support here. Roon finally finished scanning my library. Search and playback functions seem to perform well, though it could be snappier. I have ordered a more powerful machine to update the server performance.
For those with huge library, I would suggest minimum 32GB memory. On the current Windows machine, I have seen memory usage exceeds 22GB, though CPU utilization usually hoover around 30% when scanning, indicating the single thread nature of the Roon server app. I would suggest that is an area (server being a true multi-threaded app) for future optimization to improve CPU utilization and overall performance.
Now the next problem that I’m running into is Roon ARC. The iOS app report intermittent connection to the server, sometimes having difficulty finding it. Even when connected, it sometimes struggle with accessing content. This is when the server is sitting idle (i.e. not scanning or playing anything). I have Gb fiber internet connection and the server is on GbE, so what could possibly be the problem here? What should be the expected performance of ARC?