Hello. I'm thinking about making a modest all-in-one server for NAS, Apps likes plex (etc), and VMs for desktop replacements (one for casual browsing, one for gaming, one for coding, guest use, etc). I stay informed about hardware and performance, but what I don't understand is which drives I should get when using unRAID for this setup.

 

My NAS needs are very modest (2-4TB), but I need the desktop VMs to run off SSDs. I'm more concerned about putting my $ into speed and reliability than large space... My questions:

 

(1a) Since my NAS needs are low does it make sense to use 2 or 3 cheap 1TB SSDs and get a big performance improvement when the local desktop VMs are reading/writing to it (I understand that over a 1Gb ethernet connection, it wouldn't really matter)

(1b) I guess I don't need a cache drive if the NAS drives are SSD?

(1c) Or is there better performance-to-space-per-dollar if I get HDDs and a small but extra-fast cache (2.5 SSD or nvme m.2 SSD)?

 

(2) Do I buy SSD(s) separately for dedicated VM space? Or are VM allocations somehow tied to NAS space?

 

(3a) I guess I can get an HDD for parity... But does that protect both NAS and VMs? If an SSD holding a VM went down, that would seriously kill speed for all VMs on that SSD until I replace the SSD, I assume.

(3b) Does an HDD parity drive slow down the SSDs (for Nas, and for VMs) when reading/writing?

 

(5) Is there any use for the mobo's built-in raid 0/1/5 abilities?

 

Ok. Thanks for your time. I hope to join the community soon!

There are basically 3 storage classes in unRAID - the data array, the cache pool, and additional devices.  The data array officially only supports spinning HDs.  This includes the parity drive and all the data slots.  The cache pool does support SSDs, as does additional devices (which can be managed by the Unassigned Devices Plugin, acquire by installing the Community Applications Plugin).  Guest OSes can be located on the cache pool or additional devices, but the data array is usually too slow and better suited to static data - photos, music, videos, backups, etc.

 

Caveat - there are some folks who are experimenting with SSDs in the data array and it's working, but it's not supported or widely done.  The issue is trim support given the way unRAID calculates parity.

 

Regarding the motherboard RAID controller - it isn't usually used in unRAID.  unRAID is a software RAID implementation and uses devices in JBOD mode.  There are limited scenarios where someone wants to have a bunch of SSDs in a mini-array to use as the cache pool, instead of using unRAID's built in BTRFS pooling capabilities.  If so, and the RAID controller can present the array to unRAID as a single device then it's possible.  I've only seen that done via an add-in controller like Areca, though.  The standard approach is a BTRFS pool if you want multiple devices in the cache pool.

 

Hope that helps.

There is no doubt that the rapid falling price of SSDs makes these valid questions. SSDs are the top of any performance/dollar chart. Large SATA drives are the top of any GB/dollar chart.

 

1a) No, the VMs should run from SSDs, and the NAS should be bigger+slower HDD. Cheap SSDs are not a good place to start, as they are low on the performance curve. You said put money into speed and reliability, that means no cheap SSDs.

1b) True, but it is likely to be less costly to have a fast set of cache SSDs, than a full set of SSDs for everything.

1c) I think this is the route to look into, solid fast SSDs for cache, and Dockers, and VMs. Then HDD for expansive storage.

 

2) What is not clear is your space requirement for VMs, or even cache. As mentioned above, this is the area to focus on for performance.

 

3a) I would not mix SSDs and HDDs in the array, even if supported. The SSD will perform for reads, but not writes. The BTRFS based cache pool will allow the VMs to continue to run after an SSD failure.

3b) Mentioned above, I don't think it makes sense to mix SSDs and HDD in the array.

 

5) Potentially the RAID1/5 (don't use RAID0) could be used for the cache drive instead of BTRFS.

 

Roughly, I would suggest a pair of 900+GB SSDs in RAID1, for cache and VMs, and three HDDs (3TB-6TB each). But that vastly oversizes the 2-4TB as 6-12TB.

 

If you really mean 4TB max, not going to need to grow it, you might look at dropping unRAID and use a fast controller with battery backed cache and 6 or more SSDs. Without need to grow, and using all SSD, unRAID's major features (easy expansion and spin down) are not needed.

 

Also expect more real offerings in the NVMe space this year.

 

 

Just to further elaborate on what's already been said:

 

(3b) unRAID parity is realtime and any writes to any disk in the parity array will update parity at that time, so writes will never be faster than parity.

Thank y'all for the responses. I have a better idea now. My biggest takeaway is that VM space either uses the data array, "borrows" space from the cache drives, or uses a third party plugin that gives unRAID the ability to have drives "on the side" (my words).

 

Maybe something for the FAQ: "Common storage setups". One for someone who wants lots of storage, one for someone who wants all-in-one, one for speed, one for extra redundancy, etc. Just an idea.

 

Thanks again, and I'll report back if I finally put this into practice or have more questions.

I think my setup would look something like:

3x SSDs as Cache Pool and VM Space

3x HDDs for NAS

 

An important piece missing is archived backups. I like to have time-machine/file-history style archives of my files. If I weren't running unraid, I'd run a 3TB HDD for files and a 4 or 6 TB HDD to backup the files with history/archive. I'd use something like Arq to automatically backup files and VMS to the 4TB, as well as Amazon Glacier.

 

So how do I do this in unRAID? I know BTRFS has some sort of snapshot capability. I assume there are plugins to backup to Glacier... but how is the usability? I'm cautious about 3rd party plugins and manually editting config scripts (I'm capable, I just don't want that level of maintenance). Can the VMs be backed up too? I accept some loss of simplicity in exchange for unRAIDs features... I'd really love a good desktop-VM type 1 hypervisor, and unRAID seems to be it.

 

While I'm here: How is unRAID's support for nvme? I've considered using a pcie 3x4 m.2 drive like the samsung 950 or ocz RD400 as a cache drive. These drives are otherwise over kill, but (1) is their bandwidth and speed finally put to use as a VM drive + cache? Or is it still overkill? (2) What about a pool for redundancy... Could they be pooled with cheaper SSDs or am I asking too much? It seems like replacing a cache drive full of VMs would be a major hassle, and so redundancy is strongly prefered. There are good mobos with 3 pcie 3x4, but the GB/$ of these drives are outrageous.

 

Thanks, and I hope my questions aren't too tedious.

6.2 beta supports NVMe.

 

However, you really don't want to mix NVMe SSD with SATA SSD. Think driving Ferrari and get stuck behind 2 Nissan Micra on the motorway. Like that.