vertigo

Trying to figure out if unRAID is right for my needs

29 posts in this topic

5 hours ago, trurl said:

Are you sure you know how parity works? Nobody here thinks parity is a substitute for backups. But you don't need another parity drive for every data drive you add. You just need a single parity drive for the entire array. Or you can have dual parity and have 2 parity drives for the entire array if you want the ability to recover from 2 simultaneous missing disks. In fact, unRAID doesn't even support more than 2 parity drives for the entire array. You can have a single parity drive and it will provide parity protection for 20+ drives.

 

I'll have nothing more to say about parity unless you have a question about it. Just trying to make sure your decision to NOT use parity is based on a good understanding.

 

I don't really know how parity works (I have a theory, but for the time being, I'm willing to accept it as some sort of dark arts black magic voodoo, to be able to protect an unlimited amount of drives with only one drive without eating into any of the storage capacity save for the parity drive), but I do understand that it works that way. I just don't currently feel it's worth the expense when I have a backup already and would maintain that backup regardless of if I used parity. That said, if cache drives really aren't necessary, despite the fact that pretty much everything I've seen regarding unRAID says they are in order to have decent transfer speeds, then that would drastically reduce the cost and necessary drive bays and SATA ports, which would make me more open to the idea. I guess if I determine that unRAID would work for me, I'll have to do more research into that, but I'm trying to take it one step at a time for now.

 

As for your statement "Perhaps a more important use of cache these days is for dockers and VMs, since you can afford to have relatively small SSDs in cache for this purpose, and so gain a lot in performance," I have a couple questions. First of all, when you say VMs in this sentence, are you referring to the VM my gaming PC would be running in, or a VM within that VM? And would a cache SSD really be beneficial considering everything would be running off an NVME SSD, which will be much faster than a cache SSD would?

 

 

4 hours ago, tdallen said:

Yes, that's correct.  Generally, by the way, Dockers are preferred as applications over VMs if they are available.  The virtualization there is lots lighter weight.

 

If you are running VMs it is recommended to set aside at least one core (and it's hyperthreaded VCPU) for unRAID.  You can let things be a free for all and that can work for non-performance sensitive VMs that do background processing.  But for performance sensitive VMs like gaming people have had the best experience running dedicated/pinned cores for VMs under unRAID.  That gets tricky if you want to run a lot of VMs and you'll see people moving to socket 2011 and Xeon E5s in that case.

 

Ok, so instead of my initial thought of assigning a core to a NAS VM and the other 7 cores to my main PC VM, I would just assign the single core to unRAID. I have to say, I'm not fond of getting such a beastly CPU then giving up 1/7 of it, not to mention running a PC (VM) with 7 cores (the OCD in me wants an even amount), but oh well. ^_^

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Assuming you are talking about an i7 or Xeon E3, the recommendation is to assign both Core 0 and 1 to unRAID - Core 1 is a hyperthreaded core, not a real core.  And in the world of virtualization, neither the i7 or E3 are beastly - downright middle of the road at best.  14 core hyperthreaded E5's with 28 VCPUs are beastly >:D.  But the i7 and E3 have their place, since their faster clock speeds make the more suitable for performance sensitive VMs like gaming.

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Planning on using a Ryzen 7 (8-core). And yes, I realize it has nothing on a Xeon, but compared to other desktop CPUs, including the i7, it is a big step up. So I'd be assigning the first core (two threads) to unRAID, and the other 7c/14t to the main PC.

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That'll work.  Make sure to read the Ryzen thread:

 

 

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