Unraid as a gaming vm hypervisor


Nigel

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Hi,

 

I’m currently building out an ASRock  8 GPU server and have come across unraid due to the excellent passthrough support for consumer GPUs.  I’m struggling to find a definitive recommendation for the storage.  I’ve been testing with a single SSD as the data array and the whole setup works brilliantly, so I’m now looking to pull the trigger for buying storage.  

I’m only going to be running VMs on this, and I have an intel rapid storage hardware raid.  For performance, I will only look at including ssd drives, so what’s the best setup before I sink lots of money?  I was just thinking to use the hardware raid 5 with 3*1tb ssd for the data drive, but I could assign one as parity and use native unraid instead.  Does trim really matter if all there is going to be are large VM images running windows 10?

 

FYI I have 64gb ram and 2*e5-2690 v3 cpus so plenty of resources to run several gaming vms.  Obviously latest stable unraid.

 

Thanks for any advice in advance.

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  • 2 weeks later...
On 10/14/2018 at 8:28 AM, Nigel said:

Hi,

 

I’m currently building out an ASRock  8 GPU server and have come across unraid due to the excellent passthrough support for consumer GPUs.  I’m struggling to find a definitive recommendation for the storage.  I’ve been testing with a single SSD as the data array and the whole setup works brilliantly, so I’m now looking to pull the trigger for buying storage.  

I’m only going to be running VMs on this, and I have an intel rapid storage hardware raid.  For performance, I will only look at including ssd drives, so what’s the best setup before I sink lots of money?  I was just thinking to use the hardware raid 5 with 3*1tb ssd for the data drive, but I could assign one as parity and use native unraid instead.  Does trim really matter if all there is going to be are large VM images running windows 10?

 

FYI I have 64gb ram and 2*e5-2690 v3 cpus so plenty of resources to run several gaming vms.  Obviously latest stable unraid.

 

Thanks for any advice in advance.

 

Hi Nigel and apologies for not getting back to you on this sooner.

 

First and foremost, you cannot use a hardware-based RAID solution with Unraid.  Even if you managed to get it to work (which you likely won't), it is definitely unsupported.  Instead, the proper solution is to simply use individual storage devices attached to a standard SATA controller (or you can configure your RAID card to operate in SATA HBA only mode).

 

Next up is whether or not to use the array or the cache for your VM(s).  If you assign each SSD you have to disk1, disk2, and disk3 (without assigning a parity disk), then your maximum read and write speeds will always be limited to that of a single SSD.  In addition, your maximum capacity for any vdisk will be limited to what a single disk can hold, as in this configuration, you are not conjoining the disks together in a way that let's you spread blocks for a single file across multiple disks (read that as "individual files are stored on individual disks".  This may be fine for you, but there is another way you can configure the system to get RAID functionality which can increase both performance and capacity.

 

If you wish to use RAID for your VM storage, that is configured through the cache.  However, in order to create a cache pool, you must have at least one storage device assigned to the array (e.g. disk1).  If you don't really want to use array storage, you can simply attach a cheap USB flash storage device and assign that to disk1 simply to fulfill the requirement.  I'd recommend something at least 16GB in size or larger so that you can store your ISOs for your Windows installation media directly on the array device.  If you were to follow this recommendation, you should have 1 flash device assigned to the array (disk1) and 3 devices then assigned to the cache pool.

 

By default, this will configure your cache pool storage in a BTRFS RAID-1 configuration, where every block that is written will be written to two different storage devices.  This will give you a net usable capacity of 1.5 TB, but it will limit performance to approximately that of a single device.  You can adjust the RAID-mode, however, from the cache device settings page.  Just click on the first cache device and scroll down to the balance section.  From here, you can convert your RAID 1 cache pool into another RAID type.  For the fastest performance, RAID-0 would be recommended, but know that if any single SSD in your cache pool fails, you will lose 100% of your data / VMs.  RAID5/6 are possible to configure, but not necessarily recommended at this time due to stability issues.  You can configure it, but it's use at your own risk.  To change the RAID mode, paste this into the balance section (you can change the RAID0 to another type if you want):

 

-dconvert=raid0 -mconvert=raid1

 

Leave the "-mconvert" as raid1, since that's just for metadata and won't account for much anyways.

 

I hope this was helpful info!

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Hi Jon,

 

I did some more experimentation, and discovered that indeed the hardware raid was completely ignored by unraid, so I skipped on from that idea pretty quickly.

 

I've now settled on 2*2TB rotational (data+parity) with 2*1TB SSD in the cache giving me 1TB usable.  I figured the cache pool would be a little weird with an odd number of drives (5), so I just went with protected rotational (which spin down most of the time).  After migrating gaming over to the server I have freed up 2*240GB SSD drives from other PCs and they have also gone into the cache, giving me 1.2TB of mirrored space.  I really like the capability of adding differing sizes to the pool - very flexible.  I'm assuming that replacing these smaller drives in the future will be easy if we need more space, but I'm currently running at 750GB free space on the SSDs so I'm comfortable for the moment.

 

I've also got some other more work related VMs to build which will use the SSD for boot and rotational for storage, so those drives will be used too.

 

Everything is nice and quick, and performance is pretty darn close to bare metal from a user experience.

 

Pretty happy customer with unraid right now.  Can see a lot of mixed opinions on the internet about it, but the GPU passthrough has made it just about as perfect as possible.  If ESX allowed passthrough of consumer GPUs, they would have had my custom, so their loss.  Now to figure out how to migrate vmdk to unraid images...

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