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What is Unraid and how to build an Unraid media server

Show off your HTPC builds, NAS Servers, and any other hardware. Great place to ask for hardware help too.
Manni
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Re: What is Unraid and how to build an Unraid media server

Post by Manni » Thu Jan 20, 2022 5:26 pm

Hi Paul,

Thanks, the above was more an update as I was moving on with the process, just sharing progress. Yes there were many things already discussed, so I didn't spend too much time on these. Overall, there is no real issue.

Thanks for the info re tuning and check, I'll ask in the forums if things don't improve with a cache. It might be that because I had some system files in the array itself, it was trying to read files at two different places on the same disk. That's another reason why I wanted to moved system files and VMs to a cache (see below).

I have no way to know if the server was on sleep or had shut down, because when the issue happened I didn't realise it could be the S3 sleep kicking in and I simply turned it back on. However, I remember that the second time I was surprised by how quick it became accessible again, so I suspect it was simply on sleep. Since I disabled the auto sleep, I haven't had the issue. The pre-check was going fine, I just stopped it after the pre-read completed because I wanted to setup the cache and move the VM.

I found a better way to move a VM, as I also wanted to move all the system files that had been installed in the arrray and that kept some of the disks spinning (plus could cause some stutter). Here is how you do it:

1) Stop all the dockers and VMs
2) Disable the docker and disable the VMs in the settings. You shouldn't have a VM or a Docker tab in the GUI.
3) Go to shares and select "prefer" for cache for the Domains share (where all the VMs are located) as well as any other share you want to move to the cache. I selected the Appdata, ISO and the System share, plus my Multimedia share where I store the MyMovies metadata (for Dune).
4) Optional, but reset the stats that way you'll see more easily what happens in real-time during the next step (you'll see which disk is being read and the cache being written).
5) Mover should start automatically, but if it doesn't simply click on "move" in the "Array operations" of the Main tab in the GUI. When mover is working, the option is greyed out so it's easy to know if you need to help it manually or not. This should start moving all the files from the array to the cache, and you can see it in the GUI.
6) When the operation is over (no more read/writes, assuming no other user/process is accessing the array, and the "move" option isn't greyed out anymore) you can re-enable the VMs and Docker in the settings and relaunch your dockers/VMs. No paths to change manually, it's all automatic.

When that finishes, I'm going to enable the two parity disks to secure this array on this "production" server (they were disabled to speed up the data transfer process), then I'll move to the next server (to pre-test the 24-port board before I get the case next month).

By the way, re a question asked by Jamie, I realised that just as there is an "Automount" switch for the VMs, there is also an auto start setting for the array itself. You have to stop it, and it's in the settings (the first one I think). When enabled, the array auto-starts if there is no integrity issue detected with the array (such as a disk not detected, etc). As soon as everything is stable, I'll enable that option, because I find it convenient to have the array start and the VM to automount right away.

I'll do more tests with sleep, pre-clear etc on the second server as I really need this one to be operational and protected. The second one will have no data to start with, it will only be a test array.

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Pauven
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Re: What is Unraid and how to build an Unraid media server

Post by Pauven » Thu Jan 20, 2022 6:22 pm

Yeah, running VM's/Dockers on your array is not ideal. Cache should help. But many users still have stuttering just with parity check while watching, not related to cache or VM's/Dockers. Hence, the tunables. From recollection, some users never fully resolved the stuttering. Ironically, one strategy is to reduce parity check performance - the thinking here is that by reducing performance you're freeing up bandwidth to watch something.

You can also pause and resume a parity check, if needed. I've only done this once, and I think I got some fake errors at the end, so I never did it again. Maybe that would work better for you.

I think the way the new tunables and performance in general work is that it is supposed to give priority to data reads/writes, making a parity check lower priority. That makes sense, not sure if it really works that way though.

Manni wrote: Thu Jan 20, 2022 5:26 pm 4) Optional, but reset the stats that way you'll see more easily what happens in real-time during the next step (you'll see which disk is being read and the cache being written).
You can also just toggle the stats view between reads/writes and throughput:

image.png
image.png (75.57 KiB) Viewed 1790 times

Manni wrote: Thu Jan 20, 2022 5:26 pm By the way, re a question asked by Jamie, I realised that just as there is an "Automount" switch for the VMs, there is also an auto start setting for the array itself.
Yep, that's what Jamie complained isn't working. An error on startup causes it to disable or something like that. I haven't used that feature in a really long time.
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Manni
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Re: What is Unraid and how to build an Unraid media server

Post by Manni » Thu Jan 20, 2022 6:27 pm

Thanks, nice to be able to toggle between R/W and speed. I was only suggesting to reset the stats because it makes it easier to see where there is activity, but I guess using speed is nicer anyway, so I'll use that.

Pausing read-check didn't cause any issue here, as reported. I plan like you to run it weekly overnight anyway, so it's unlikely to be an issue.

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Pauven
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Re: What is Unraid and how to build an Unraid media server

Post by Pauven » Thu Jan 20, 2022 7:10 pm

Manni wrote: Thu Jan 20, 2022 6:27 pm I plan like you to run it weekly overnight anyway, so it's unlikely to be an issue.
Just monthly, not weekly. The default is on the 1st of the month at 2am. I changed it to the 11th at 2am. Not quite sure why anymore, but somehow the 1st of the month always seemed to coincide with me wanting to watch something, and the 11th less so. Or maybe it's my imagination. Regardless, something that only happens once a month is easy to navigate around, I pretty much never notice anymore.

If you set up the notifications, you'll have a nice email when you wake up, reminding you the parity check started at 2am. That always helps me plan around it. My parity checks take 17hours 36 minutes, give or take a few seconds, so they usually wrap up just before a prime 8pm viewing window.

For me, navigating around it isn't so much not watching anything until 8pm, but rather avoiding unnecessary writes during the day. Any writes to the array will dramatically slow down the parity check progress during the duration of the write. So if I write a lot of data during a parity check, it might not complete until well after 8pm. But I will allow writes to the cache drive, as those won't hit the array until the following morning. Actually, from that perspective, I try harder not to write to the cache on the 10th, as the mover kicks off around the same time as the parity check, and then they're competing for resources.

You're lucky, though, as it sounds like your parity check may finish much, much faster, probably early afternoon.

I recall that Johnny Walker has an SSD based server (which technically is not properly supported in Unraid), and his parity check completes in like 2 minutes. That's the dream...
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Manni
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Re: What is Unraid and how to build an Unraid media server

Post by Manni » Thu Jan 20, 2022 7:32 pm

Yes sorry I meant monthly. Thanks for the info, the first thing I setup is notifications, I use it all the time and have done so on all my servers. Wouldn't live without that :)

I guess another option is to start mover manually on the 10th before you go to bed. Unless you've written huge amounts, it should complete quickly that way there won't be any fight for resources.

Jamie
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Re: What is Unraid and how to build an Unraid media server

Post by Jamie » Thu Jan 20, 2022 8:02 pm

Manni wrote: Thu Jan 20, 2022 5:26 pm
By the way, re a question asked by Jamie, I realised that just as there is an "Automount" switch for the VMs, there is also an auto start setting for the array itself. You have to stop it, and it's in the settings (the first one I think). When enabled, the array auto-starts if there is no integrity issue detected with the array (such as a disk not detected, etc). As soon as everything is stable, I'll enable that option, because I find it convenient to have the array start and the VM to automount right away.

I do the set the autostart setting to "Yes" in the disk settings file but but on bootup it get's set back to "No". I get an error in the log that the "file" is a folder so it can't act on it. I think the disk settings file is some way corrupt so any new setting doesn't take. It is on my mind to place a question in the unraid forum but I am dealing with "non PC" issue right now.

Jamie

Manni
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Re: What is Unraid and how to build an Unraid media server

Post by Manni » Thu Jan 20, 2022 8:28 pm

Parity rebuild has started with the two parity drives. As expected, nice to see that there is no performance bottleneck, a nice 1.6GB/s for the 10 drives with 160MB/s per drive. Even with 16 drives, there wouldn't be any bottleneck as we'd be under 4GB/s, the max for this board being 6GB/s. So happy with the 9201-16i for now, especially as all the drives go to sleep now.

The 9305-24i has a 12GB/s bandwidth, so I certainly won't reach that even with 24 drives.
Parity check speed.JPG
Parity check speed.JPG (72.78 KiB) Viewed 1775 times
Everything seems to be working, so I'll update if/when there is anything worth reporting.

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Pauven
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Re: What is Unraid and how to build an Unraid media server

Post by Pauven » Fri Jan 21, 2022 11:33 am

Nice!

Manni wrote: Thu Jan 20, 2022 8:28 pm The 9305-24i has a 12GB/s bandwidth, so I certainly won't reach that even with 24 drives.
I don't believe that is correct. The 9305-24i has a PCIe 3.0 x 8 connection. Should max out just under 8GB/s:

image.png
image.png (114.81 KiB) Viewed 1768 times

But your point is still valid, even 24 HDD's won't max that out, as that permits 333 MB/s per drive.
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Manni
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Re: What is Unraid and how to build an Unraid media server

Post by Manni » Fri Jan 21, 2022 1:46 pm

I think it's more complex that that... :)

They advertise the bandwidth as 12GB/s (that's the official specs), see https://www.broadcom.com/products/stora ... s-9305-24i, that's the way they describe it, including in the PDF that you can download on that page.

However the actual throughput seems to be 6400MB/s, so below the max bandwidth of PCI 3.0 8x:

"Introducing the industry's first single-chip, low-profile 24-port SAS/SATA HDD and SSD direct attach Host Bus Adapter. Using the SAS3224 IOC, this HBA achieves over 1.5 million IOPs with minimal latency and 6,400 MBps throughput performance. The SAS 9305-24i HBA enables data center scaling by offering the ability to connect up to 24 SAS or SATA drives directly or achieve maximum connectivity through expanders."

Anyway, I was using the 12GB/s moniker because the "lower" models are advertised for 6GB/s. Not that I'll need any of that even with 24 HDDs. As long as the HDD speed is below around 260MB/s, there shouldn't be any bottleneck.

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Pauven
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Re: What is Unraid and how to build an Unraid media server

Post by Pauven » Fri Jan 21, 2022 2:46 pm

Manni wrote: Fri Jan 21, 2022 1:46 pm They advertise the bandwidth as 12GB/s (that's the official specs)
12 Gb/s SAS-3, not 12 GB/s, so 1.5 GB/s. This is the max speed per SAS-3 drive, but you won't get anywhere near that with the SATA based drives you'll be using. And even if you did have SAS-3 drives, you could only achieve this throughput on up to 4 of them at any one time, before hitting bottlenecks.
Manni wrote: Fri Jan 21, 2022 1:46 pm Anyway, I was using the 12GB/s moniker because the "lower" models are advertised for 6GB/s.
6 Gb/s, not GB/s. Case is important. There are 8 bits in a byte, so 1 GigaBytes/s = 8 Gigabits/s.

It's a ridiculous nomenclature, they really should have used different letters instead of different case to distinguish between (b)its and (B)ytes. Manufacturers seem to enjoy playing this up, though, often touting Gb/s because they can use 8x higher numbers.

To add to the confusion, there are also GibiBytes (GiB) and Gibibits (Gbits), which are very similar, but binary 1024-based instead of metric 1000-based. At least these are more clear, GiB and Gbits are case insensitive, but they look like alternate spellings and typos of GB and Gb, which they are not.

Probably more than you ever wanted to know...

Manni wrote: Fri Jan 21, 2022 1:46 pm However the actual throughput seems to be 6400MB/s, so below the max bandwidth of PCI 3.0 8x:
I wonder if they factored in overhead. A 20% overhead would drop your 8 GB/s down to 6.4GB/s, and from recollection that sounds about right for SAS/SATA.
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