Basic Unraid questions - New user

[Coshy93]

Hi all,

 

I've come from IT a few years ago (Mostly workshop activities, home server setup and maintenance and fully Apple certified) and looking at running an Unraid box. Partially for the learning and fun and partially because, well, it'll be cheaper than buying a Qnap and i have plenty of random sized hard drives and HDD bays in my case. 

 

I understand that as far as drives go, Unraid writes directly to a drive and if you had 5 drives and no parity drive and a drive failed, you still have 4 x drives worth of accessible data. My questions are:

 

1. I've read that you only need a parity drive, the size of your largest drive. So, what happens if i have 4 x 8TB drives, 3 x 6TB drives and 2 x 4TB drives with a single 8TB parity drive. How can that single 8TB parity drive hold enough info to rebuild any one of those drives? I'm assuming that the instructions of parity are not the same size as the data. So, assuming that to rebuild a 4GB movie, you do not need 4GB worth of parity information. But where do you draw the line? Where does a parity drive become too small for your array? (Or is this a case of some information is worse than none and i'm over thinking it?) 

 

2. If i set a cache SSD of 60GB and transferred 40GB up front and then 50GB moments later, what happens? Does 60GB go to the cache and then the remainder get flicked directly to the array? (WIth the cache eventually moving to the array) 

 

3. I tried setting up a Windows 10 VM. Now, i stuffed up and was running Unraid off of my GPU. I tried to passthrough the GPU to the VM and when i ran it, surprise surprise, the system crashed. (Didn't include a Vbios). I went into the BIOS and forced on board and tried again. The VM seemed to boot to a virtual BIOS? I selected a Windows 10 ISO in the setup panel etc. but not sure if it was my little mishap with the GPU (as in, a hardware VM issue causing BIOS) or perhaps a bad iso? I was running out of time last night so gave up on the idea for now, but keen to hear theories and things to try. 

 

Was toying with the idea of NAS and gaming machine or NAS and HTPC, depending on gaming performance as to which machine gets unraid and the HDD's.

 

Thanks all! 

[Kevek79]

Welcome to the forum.

 

ad 1: I would suggest you watch one of spaceinvader's fabolous videos on how the Unraid Array works to get a better understanding.

All about the Unraid Array

 

ad 2: This depends on how your mover schedule is set up. For initial data load to the array it is suggested to skip the cache drive and write directly to the array.

 

ad 3: Again I would route you to some of spaceinvaders videos ;).

Introduction in VM on Unraid

WIN 10 VM as a daily driver

WIN 10 VM part 2

 

Hope that helps a bit.

Edited July 23, 2020 by Kevek79

[Coshy93]

Thanks so much! Have seen a few Linus Tech Tips videos referring to Unraid but never heard of spaceinvaders - Will check those out! Thanks!

[testdasi]

55 minutes ago, Coshy93 said:

1. I've read that you only need a parity drive, the size of your largest drive. So, what happens if i have 4 x 8TB drives, 3 x 6TB drives and 2 x 4TB drives with a single 8TB parity drive. How can that single 8TB parity drive hold enough info to rebuild any one of those drives? I'm assuming that the instructions of parity are not the same size as the data. So, assuming that to rebuild a 4GB movie, you do not need 4GB worth of parity information. But where do you draw the line? Where does a parity drive become too small for your array? (Or is this a case of some information is worse than none and i'm over thinking it?) 

 

2. If i set a cache SSD of 60GB and transferred 40GB up front and then 50GB moments later, what happens? Does 60GB go to the cache and then the remainder get flicked directly to the array? (WIth the cache eventually moving to the array) 

 

3. I tried setting up a Windows 10 VM. Now, i stuffed up and was running Unraid off of my GPU. I tried to passthrough the GPU to the VM and when i ran it, surprise surprise, the system crashed. (Didn't include a Vbios). I went into the BIOS and forced on board and tried again. The VM seemed to boot to a virtual BIOS? I selected a Windows 10 ISO in the setup panel etc. but not sure if it was my little mishap with the GPU (as in, a hardware VM issue causing BIOS) or perhaps a bad iso? I was running out of time last night so gave up on the idea for now, but keen to hear theories and things to try. 

Answers to your questions:

1. This is a common misconception. Reconstruction is not based solely on parity. It's based on parity + the remaining working drive (i.e. everything EXCEPT the failed drive). It's the magic of mathematics (mainly the xor operation). So to reconstruct let's say a 4TB in your scenario, it would need the first 4TB data of the parity 8TB, the other 3x 8TB, 3x 6TB and the entire remaining 4TB. You can probably see why parity has to be at least as large as the largest data drive.
   Note also that reconstruction is disk-based and not file-based i.e. you can't recover a single file.
2. It depends on whether the mover is triggered. Without the mover, 60GB will be written and then out of space error. If you run the mover in between the 2 transfers then 40GB in the array and 50GB in cache (until you run the mover again then 90GB in array and none in cache). That is assuming you use cache = yes in the share settings.
3. Probably misconfiguration of the VM settings boot order.

A few additional tips:

• Definitely watch a lot of the SpaceInvader One tutorials on Youtube. Linus did his job in drawing attention to Unraid. SIO does the hand-holding.
• If you have issues, it's generally a good idea to attach diagnostics in your post (Tools -> Diagnostics -> attach entire zip file). It contains lots of information that help with troubleshooting stuff.

[Coshy93]

Thanks for that! that helps with the parity question.

 

So, with the VM, last night i watched and followed the SpaceInvader One tutorials which were helpful. Unraid certainly could have done a slightly better job of clarifying things but, i suppose it's aimed at people that already have half an idea.

 

So, all was going well through the first VM setup video. I had my VM booting with VNC graphics and input etc. and installed drivers and OS tweaks.

 

Next comes the passthrough video, following it step by step and, no display output when it comes time to start. I was using the GPU for Unraid and the VM and used the BIOS that i grabbed out of GPUz. I also, for peace of mind, grabbed a confirmed UEFI enabled bios from Techpowerup, but this didn't help. 

 

I went back into my BIOS, forced onboard and rebooted. Unraid is now using my onboard. I've removed the BIOS file as i assume it is one more thing that can go wrong and tried to boot. The machine booted the Windows automated start up repair! Success! Or so i thought..

 

I shut it down from here and went again, for a normal start up. I got the Windows 10 spinning wheel for about 1 second and it froze. I'm sure i read something somewhere before this mentioning that there is something to try when / if this happens, but i can't recall what it was and can't find it.

 

Intel VT-D is enabled in BIOS and IOMMU is enabled in Unraid.

 

My GPU display is in its own IOMMU group and the audio side of it is in the next IOMMU group. Unsure if this would cause an issue? In the SpaceInvader videos, he mentions enabling ACS override, but it looks like Unraid has been updated since the video and i had 3 options to pick from, so i went with "both".

 

Any advice is appreciated. Currently at work so a log dump isn't possible, but can get one next time i try if this would be best? 

[Coshy93]

For anyone that came across this, i got it working in the end! Had to create a new VM (Was able to point it to the same VM HDD so that re installation wasn't required) and had to select Q35 instead of i440. Everything now works fine!