DesertSweeper

The box was supremely reliable and only fell over on account of my own stupidity...the RAID-5 overflow problem is well known with NAS4FREE. AM going to transplant the drives back into her again tomorrow and see how it goes. Still have my backup so no big issue if it falls over again

Thank you JB, was that a large'ish array like mine of 6 x 6TB drives? Does it make any difference like it does with ZFS? I guess it just the question of parity writing...

So the main issue I have run into now with unRaid has nothing to do with unRaid...as I said when I started, my journey began with a failed NAS4FREE server that ran flawlessly for many many years. And it only died because one day I copied a huge chunk of 4K GoPro footage to it without realising that the 24TB of RAID-5 space was maxed out. It fell over and corrupted the array. Took me a few weeks to recover all the data which I did and then re-formatted the little box with a ZFS array which is apparently more robust. That created a new problem - the HP Microserver N40L (AMD 2.2Ghz Turion) did not have enough juice to handle ZFS. Despite have 16GB of ECC RAM it was maxed out dealing with ZFS issues. I could either go RAID-5 again or look at an alternative host. So I dug an old HP Proliant ML110-G7 out of my store that had been decommissioned and chucked out by a client. It has a decent Quad-core Xeon (E30-1220) and 24GB of ECC RAM. That would surely have enough power to deal with ZFS on NAS4FREE. I transferred the 5 6TB WD Red drives and added a 6th since there was enough space in the mini-tower. And then I visited a friend who uses unRaid and that got me thinking - it makes so much sense. Which is where my grumpy opening statement came from. Misguidedly yes. But all that aside this ML110-G7 is a noisy power-hog. I do not need any VM's or anything else fancy. I have a small and powerful ESXi hypervisor box that does that for me. I just want a low-powered high-capacity NAS that sucks up my GoPro footage quickly (hence the cache concept). If I chuck it all back into the baby N40L that hosted the NAS4FREE all these years, will it perform ok for pure SMB-share on that low-end CPU?

I did actually try to do that but there does not seem to be a way of doing it

I discovered "Spaceinvader One" - a gold mine of tutorials. For now I have disabled the cache as I copy 20+ TB of data from external backup drives to the new server. Once I am back up and running I will roll-up my sleeves and go through all the suggestions in this thread and do things properly. Many thanks for all the suggestions.

On further reflection I absolutely agree with your analysis in the performance stakes. My thinking was clouded by a typical Cache-controller where the processing is off-loaded from the main cpu.

I installed two Samsung 500GB SSD's in a RAID-1 PCI-E dedicated card, to provide peace of mind for this issue. I typically dump between 100 and 200 GB of video data from my GoPro in one job that would typically fit in the cache.

Thank you for clarifying. Wouldn't it be great if Limetech just had a tick-box during installation that said "I want to use {specified target} as a pure transparent caching drive." End of issues, no grumpy forum threads. No support requests. In the world of enterprise computing a cache drive is just that - a high speed broker that is transparent. If you want to roll up your sleeves and play with VM's and the like - by all means dig in to the settings. But I am guessing the majority of home NAS users just want to accelerate their write speeds out-of-the-box. Anyway enough of that. I will persevere

Thank you constructor - I have now turned it back on and can see it is flushing. Many thanks again. With regard to my opening statement and some of the snarky comments that followed I just want to say that this is a paid-product. It is not a hobbyist platform like freenas et al. And I stand by my opening statement that I believe the caching setup should just work out-of-the-box in a usable way. It is what I am willing to pay for. I believe an added cache should flush in the background in idle moments without you having to do anything. It just makes sense. That aside I apologise for coming off as harsh and appreciate all the help received from those who give it.

Actually I tried everything including "prefer" and finally just turned it off - yesterday. But it still will not flush. I think the best thing to do is just delete all the data and re-install it and start over with the cache disabled. Once all the data is restored, enable the cache and perform the recommended adjustments/plugins mentioned herein.

Thank you for your rapid response Constructor. diags file attached. nas01-diagnostics-20190804-0417.zip

Well yes I am back. And I don't peruse religious forums. And I do not live on forums - I seek a working solution for which I am more than happy to pay. Things are worse now. I am unable to get it to commit the contents of my SSD Cache to the main array. It is just sitting there at 499GB of 500GB. I have tried to manually trigger the scheduler, have set it to hourly, but one full day later and it is still sitting at full. I was patiently waiting for it to flush the contents so I could try the suggestions. When I view the main-array share from a client I see all the data, including that of the cache. So I assume it is transparently presenting a unified data-set. I have the original data on my backup so I guess I can wipe the whole lot and start again...

My ancient but trusty NAS4FREE server finally expired and I decided to build a new NAS for my home use. UNRAID is a compelling option - it has paid support and is an absolute breeze to set up. But it has one massive failing for me - that cache methodology is just plain horrible. Why on earth does it rely on a scheduled "mover"? Why not just update the storage array in idle time - or when it nears full? You go to copy a chunk of files and it all falls apart when it hits the SSD's capacity. And yes I get that you can turn it off, but do I really want to have to go and log in to the GUI and try to remember where that setting is each time I decide to dump the contents of my external drive or something? No I want what NAS4FREE gave me - a seamless box that lives in the depths of my store-room which I occasionally have to power down if there is going to be an extended power-outage. Like once a year. Damn but it is so close to being a perfect solution...back to NAS4FREE for me. Thanks for the trial version. EDIT: After some patience and fine lovin' from forum members I have come to understand things differently