Is storage spaces flexible enough for me?

[Frozennova]

I currently have a custom build home server based on a dual core and chip with an Intel nic running esxi, which then runs FreeNAS and a couple of other vms and currently have 2x1tb drives in a ZFS pool.

The plan is to run an 8 drive array eventually with 2 parity drives. However I'm at a point where my current storage needs are close to exceeding to storage space I have, but I haven't got the funds to drop on 8 drives and a controller card in one go.

I could go out and buy another drive to add to the pool but that presents me with two problems, firstly it means i still haven't got any redundancy and secondly once I have built my 8 drive array the 3+ disks in the pool cannot be added back to the RAIDZ2 array to increase capacity or the number of parity drives.
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Is it possible with storage spaces to start with a JBOD type pool of drives then at a later date stick another drive in the system and add that as a parity disk or does it have the same limitation as ZFS whereby once the array is created as a JBOD I'm stuck with it being a JBOD array.

 

[Frozennova]

I had a play earlier using VHDs and I can't do what I was hoping for.

The goal or this wad primarily to move away from virtualising the NAS part of the software while still being able to run a few pieces of windows specific software. So even as you say flexraid will achieve what I was hoping for in terms of disks I'm still going to have to virtualise the file storage.

EDIT : just took a quick look at flexraid and it appears it isn't quite what I though and will do what I wanted to achieve. Is flexraid going to be happy to take my existing drives that are ZFS formatted and holding data?

EDIT EDIT: More think etc. I honestly think my current setup is heading in the right direction. I'm simply not going to be able achieve all of what I want without some. From some reading flexraid has a lot of niggles and bugs which cause a lot of problems. I think ill stick with ESX, FreeNAS and server 2012 as it's setup now.

Change the motherboard to something that supports IOMMU and buy a dedicated SATA controller as intended and pass that through to FreeNAS

 

[Frozennova]

I know I can use ZFS in that way

I was hoping for a solution whereby I could add more physical drives.

I would like to run an 8 drive RAIDZ2 when the server is full populated but I can't afford £750 on drives a sata controller and a motherboard that allows hardware pass through.

At the moment I'm running two drives in a pool which is nearing being full so I'll add another drive to that pool.

I was hoping I could gradually build the number of physical disks to boost the amount of storage I have.

However I think I've found a solution with ZFS that achieves as close to possible as I would like by pooling two raidz1 arrays and a RAIDZ mirror.

 

[Frozennova]

Would I be right in thinking that this setup would give substantially better write speeds than the original planned 8 drive RAIDZ2 array, and also slightly more redundancy against drive failure.

Although as this is purely for backup and media storage disk performance isn't a huge issue.