I am exploring the possibility of building a VM server based on FreeNAS. My current system runs on Ubuntu server (not using ZFS), and I also have a FreeNAS build to handle my local file sharing needs, which I only mention as a means to say that I have just enough experience with FreeNAS to be both intrigued and dangerous.
On to my specific question. In my Ubuntu system, I run the VMs off of a single SSD that's backed up periodically to my FreeNAS network storage. From what I've read in cyberjock's extremely helpful slideshow in the Help & Support forum, it would not be advisable to create a single disk zpool on FreeNAS to handle this function due to the way that ZFS relies on redundancy to protect against data corruption. That being said, I'd like to build an economical zpool to host these VMs that balances redundancy, speed, and cost. My initial thought is to build an array with two matched pairs of drives (one pair made up of HDDs and one pair made of SSDs) that would be placed in RAIDZ1. For example: 2 x 1TB SSDs + 2 x 1TB HDDs. In my mind, the HDDs in this configuration would be a cheap way to add the necessary redundancy without incurring much of a speed penalty (when compared with my current single SSD setup) thanks to the data being spread across multiple drives. Am I correct in this line of thinking?
I've looked around to see if anyone else talks about doing something similar to this, but so far the only posts I've found in the forum were people wanting to mix and match old drives that weren't the same nominal size, and none of them were planning to use said mixed zpool for VMs or jails. In those instances, I completely understand why it is not recommended to mix the drives, but for my use case, the only drawback that I can foresee is losing a little bit of usable space if the SSDs and HDDs aren't identically sized. Since I'm not all too worried about that (maybe I'll use that extra space for swap if I can figure out how to do that in FreeNAS), is there any other major reason I shouldn't try this disk arrangement? Am I making this more complicated than it has to be? Should I just go with the single SSD and keep regular backups on the network storage? Any experienced insights would be welcome!
P.S. Just for reference, the system I would be building on is an HP Z620 workstation with a single Xeon E5-2670 processor and 64 GB of ram.
On to my specific question. In my Ubuntu system, I run the VMs off of a single SSD that's backed up periodically to my FreeNAS network storage. From what I've read in cyberjock's extremely helpful slideshow in the Help & Support forum, it would not be advisable to create a single disk zpool on FreeNAS to handle this function due to the way that ZFS relies on redundancy to protect against data corruption. That being said, I'd like to build an economical zpool to host these VMs that balances redundancy, speed, and cost. My initial thought is to build an array with two matched pairs of drives (one pair made up of HDDs and one pair made of SSDs) that would be placed in RAIDZ1. For example: 2 x 1TB SSDs + 2 x 1TB HDDs. In my mind, the HDDs in this configuration would be a cheap way to add the necessary redundancy without incurring much of a speed penalty (when compared with my current single SSD setup) thanks to the data being spread across multiple drives. Am I correct in this line of thinking?
I've looked around to see if anyone else talks about doing something similar to this, but so far the only posts I've found in the forum were people wanting to mix and match old drives that weren't the same nominal size, and none of them were planning to use said mixed zpool for VMs or jails. In those instances, I completely understand why it is not recommended to mix the drives, but for my use case, the only drawback that I can foresee is losing a little bit of usable space if the SSDs and HDDs aren't identically sized. Since I'm not all too worried about that (maybe I'll use that extra space for swap if I can figure out how to do that in FreeNAS), is there any other major reason I shouldn't try this disk arrangement? Am I making this more complicated than it has to be? Should I just go with the single SSD and keep regular backups on the network storage? Any experienced insights would be welcome!
P.S. Just for reference, the system I would be building on is an HP Z620 workstation with a single Xeon E5-2670 processor and 64 GB of ram.