SSD, HDD, and cache


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Hello unRAID community.

 

I've decided to go with WD Red, maybe even Pro for storage for my future NAS.

I want a silent system, and the specifications says WD is more silent, and the failure rate is lower if I remember correctly.

I'm still searching on input regarding the storage, so WD vs Seagate.

 

Also, I think I'm gonna go for either a normal SSD or NVME SSD for the OS, depending on if I go with my current system, or a complete new one.

 

For the cache, I'm thinking of using a second SSD or something, so I can put all games there so I don't have to download updates to my Steam library directly from Steam, but from the NAS instead.

 

If you have any input on it, like what your process was, and what you ended up with, and why, I would really appreciate it.

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My 2p:

  • If you are after silence (and not performance), use WD Red for the array (i.e. don't get the Pro). There's quite a cult following of WD Red for Unraid.
  • Brand is practically irrelevant in recent years when it comes to failure rate. So I would say just get whichever one you are most comfortable with and within your budget. It's more important that you:
    • Buy from a reliable source (so you can claim warranty)
    • Preclear (i.e. stress test) each disk before adding to the array - "infant mortality" rate of HDD is not insignificant
  • If you intent to pass through an NVMe SSD to a VM using the PCIe method, make sure you double check that it can be passed through (e.g. Intel 660p, 760p don't work). The most ideal case is if there's another forum user who has had success passing through the same SSD you are after.
    • Do NOT get an NVMe SSD unless you intent to pass it through via PCIe method. Any other method has a negative impact on performance (if not immediately then down the line). Most of the time the impact isn't that perceptible but then if you aren't about maximum performance then may as well get a SATA SSD for cheaper.
  • Don't get QLC SSD (e.g. Samsung QVO, Intel 660p etc.) for VM boot and/or Unraid cache.
    • QLC is meant for large capacity storage (think SMR for HDD) and not for RW IO.
    • Go for 3D TLC or "V-NAND" instead.
  • Steam library is generally better in the array for games that you don't play and cache for games that you play often. I vaguely remember there's a guide post / video for it.
  • Have at least 500GB SSD for your cache. The cache has evolved to becoming essential for full utilisation of Unraid. Having a small cache pool just cause headaches down the line.

 

 

 

Edited by testdasi
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53 minutes ago, testdasi said:

My 2p:

  • If you are after silence (and not performance), use WD Red for the array (i.e. don't get the Pro). There's quite a cult following of WD Red for Unraid.
  • Brand is practically irrelevant in recent years when it comes to failure rate. So I would say just get whichever one you are most comfortable with and within your budget. It's more important that you:
    • Buy from a reliable source (so you can claim warranty)
    • Preclear (i.e. stress test) each disk before adding to the array - "infant mortality" rate of HDD is not insignificant
  • If you intent to pass through an NVMe SSD to a VM using the PCIe method, make sure you double check that it can be passed through (e.g. Intel 660p, 760p don't work). The most ideal case is if there's another forum user who has had success passing through the same SSD you are after.
    • Do NOT get an NVMe SSD unless you intent to pass it through via PCIe method. Any other method has a negative impact on performance (if not immediately then down the line). Most of the time the impact isn't that perceptible but then if you aren't about maximum performance then may as well get a SATA SSD for cheaper.
  • Don't get QLC SSD (e.g. Samsung QVO, Intel 660p etc.) for VM boot and/or Unraid cache.
    • QLC is meant for large capacity storage (think SMR for HDD) and not for RW IO.
    • Go for 3D TLC or "V-NAND" instead.
  • Steam library is generally better in the array for games that you don't play and cache for games that you play often. I vaguely remember there's a guide post / video for it.
  • Have at least 500GB SSD for your cache. The cache has evolved to becoming essential for full utilisation of Unraid. Having a small cache pool just cause headaches down the line.

 

 

 

testdasi, from what I remember, as long as there's not 5 streams of 1080p at the same time, from the same drive, it should be fine.

Why shouldn't I go for the Pro drives?

 

I'm always buying from a Danish retailer with good RMA, so I won't have any issues in case it should be there.

 

I don't know if I need or want NVME yet, it was just an idea to get good speeds for the cache.

So, I can't use the cache for getting updates so I won't have to download them from a Steam server? Or did I misunderstand what you meant?

 

I'm thinking 1 TB of storage for the cache.

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22 minutes ago, Nanobug said:

testdasi, from what I remember, as long as there's not 5 streams of 1080p at the same time, from the same drive, it should be fine.

Why shouldn't I go for the Pro drives?

 

I'm always buying from a Danish retailer with good RMA, so I won't have any issues in case it should be there.

 

I don't know if I need or want NVME yet, it was just an idea to get good speeds for the cache.

So, I can't use the cache for getting updates so I won't have to download them from a Steam server? Or did I misunderstand what you meant?

 

I'm thinking 1 TB of storage for the cache.

Pro is more expensive with better performance (7200rpm vs 5400rpm) but if you aren't requiring it then there's no point getting it.

That's why I specifically caveated that as long as you are after quiet and not performance. My old Seagate Archive (5900rpm) can handle 5 simultaneous 1080p streams easily but I understand it does depend on the actual bitrates.

 

You can use the cache for anything you want really but you probably prefer prioritising it for things that actually require better performance. You CAN use the cache for what you said, it's just that IMO the array probably is sufficient.

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21 minutes ago, testdasi said:

Pro is more expensive with better performance (7200rpm vs 5400rpm) but if you aren't requiring it then there's no point getting it.

That's why I specifically caveated that as long as you are after quiet and not performance. My old Seagate Archive (5900rpm) can handle 5 simultaneous 1080p streams easily but I understand it does depend on the actual bitrates.

 

You can use the cache for anything you want really but you probably prefer prioritising it for things that actually require better performance. You CAN use the cache for what you said, it's just that IMO the array probably is sufficient.

I guess I'll have to check what the bit rates are on each video then.

 

So, the cache can be spread across the number of drives I have?

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2 hours ago, Nanobug said:

I guess I'll have to check what the bit rates are on each video then.

 

So, the cache can be spread across the number of drives I have?

The cache pool is separate from the array. To simplify things, usually people have the HDD in the array and the SSD in a cache pool (which may have 1 or multiple SSDs).

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30 minutes ago, Nanobug said:

I need a new USB stick then

Because of the limited interactions with the stick, endurance is much more important than speed. I recommend https://www.kingston.com/us/usb-flash-drives/datatraveler-se9-usb-flash-drive

They have a metal shell, which is good for heat dissipation and physical protection, and USB2, to help with compatibility. The 16GB version is more than generous, typically you will use less than 2GB of space for unraid and all the settings and customizations. The vast majority of add on programs will live on the cache drive.

 

You want to avoid the super micro miniature USB 3 drives, the heat has nowhere to go, and they tend to cook themselves.

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8 minutes ago, jonathanm said:

Because of the limited interactions with the stick, endurance is much more important than speed. I recommend https://www.kingston.com/us/usb-flash-drives/datatraveler-se9-usb-flash-drive

They have a metal shell, which is good for heat dissipation and physical protection, and USB2, to help with compatibility. The 16GB version is more than generous, typically you will use less than 2GB of space for unraid and all the settings and customizations. The vast majority of add on programs will live on the cache drive.

 

You want to avoid the super micro miniature USB 3 drives, the heat has nowhere to go, and they tend to cook themselves.

So I can't use a USB 3 stick?

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15 minutes ago, Nanobug said:

I might be a bit stupid here. But why 2 over 3, does it matter that much if you don't take the speed into account?

You can use USB 3 sticks. There is nothing inherently wrong with it on paper.

The speed advantage of USB 3 over USB 2 is virtually irrelevant to Unraid with the only benefit happens at boot (less than 10s faster boot based on my own testing) and ONLY at boot.

What we have noticed over the years is that USB 3 seem to have the higher tendency to have issues.

  • Anecdotal failure rate over time seems to be higher. It could very well be that USB 3 sticks are more common and thus people tend to report them failing more often. Another hypothesis is that USB 3 is faster but generates more heat and heat is bad for electronics (e.g. causing data corruption, random disconnects etc.).
    • That's why Jon recommended a big stick with metal shell to help with heat dissipation.
    • If you can't get USB 2 stick then at least use the USB 2 port on your motherboard. Slower = less heat = better.
  • Some motherboards / chipsets don't like booting from USB 3 ports. It could very well be an early adopters' issue a long time ago and may not be an issue anymore.
  • USB 3 also has more connection points than USB 2 and the more connections, the higher chance of something failing. So just by probability alone, sticking (pun not intended) to a simpler design reduces chance of failure.

Anecdotally though, there are people running mini USB 3 stick for years with no issue. It's a probability and luck thing.

 

The only USB stick that you absolutely CANNOT use with Unraid is one without GUID (most cheapo / unbranded sticks you get out there are likely to NOT have GUID).

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14 minutes ago, testdasi said:

You can use USB 3 sticks. There is nothing inherently wrong with it on paper.

The speed advantage of USB 3 over USB 2 is virtually irrelevant to Unraid with the only benefit happens at boot (less than 10s faster boot based on my own testing) and ONLY at boot.

What we have noticed over the years is that USB 3 seem to have the higher tendency to have issues.

  • Anecdotal failure rate over time seems to be higher. It could very well be that USB 3 sticks are more common and thus people tend to report them failing more often. Another hypothesis is that USB 3 is faster but generates more heat and heat is bad for electronics (e.g. causing data corruption, random disconnects etc.).
    • That's why Jon recommended a big stick with metal shell to help with heat dissipation.
    • If you can't get USB 2 stick then at least use the USB 2 port on your motherboard. Slower = less heat = better.
  • Some motherboards / chipsets don't like booting from USB 3 ports. It could very well be an early adopters' issue a long time ago and may not be an issue anymore.
  • USB 3 also has more connection points than USB 2 and the more connections, the higher chance of something failing. So just by probability alone, sticking (pun not intended) to a simpler design reduces chance of failure.

Anecdotally though, there are people running mini USB 3 stick for years with no issue. It's a probability and luck thing.

 

The only USB stick that you absolutely CANNOT use with Unraid is one without GUID (most cheapo / unbranded sticks you get out there are likely to NOT have GUID).

I didn't think of it that way, but it makes sense. But you could argue, that manufacturers (hopefully) gets better at their job.
But I'll get a DataTraveler SE9 2.0 USB. I've already found one with 16 GB, and it's like $10 + shipping here in Denmark, so I'll just use that.

Thank you for clarifying and  helping out, it's really appreciated :)

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