SOLVED Upgrading pool. RaidZ2 vs mirror vdev

[BloodyBonkers]

Hello. I currently have an hp microserver g8 equipped with a 1265L and 16GB of ram. (I intend to buy a motherboard for this CPU/RAM combo so I can place my rig in a define r5 or a rack case, but cannot afford this right now)
My current storage config is 3 WD red 2TB's in raidz1. for about 3.6TB of "usable" space. I do kind of find it a bit unsettling to use only raidz1 and am looking to go for a solution with higher redundancy.

After a flash sale, I managed to order myself a couple Ironwolf 2TB's (I would have preferred reds but this was considerably cheaper at the moment).

For now, I think I will only use 4 of the total 5 drives. (consider two use cases for the last drive 1. spare drive in case of failure. 2. used as hypervisor storage instead of iSCSI from freenas)

I have seen some discussion regarding the use of mirror vdevs vs raid6 and would like some input on a couple things.
-Whether you think mirror vdev's are sufficiently reliable when it comes to the risk of a second drive failing during a rebuild.
-Which one will be more suitable for my use? i.e. nextcloud <-> smb archive storage (famliy photos etc.), iSCSI for hypervisor/vm's (running unifi controller, + game servers)
-what performance numbers would I be looking at for both raidz2 and mirror vdev over a 10gbe connection. A rough estimation is ok.

In any case thanks for taking the time to answer.

EDIT: forgot to mention I will be running a PLEX server on it.

 

[kdragon75]

-Whether you think mirror vdev's are sufficiently reliable when it comes to the risk of a second drive failing during a rebuild.

Its much better than a RAIDz1 but not as good as RAIDz2 as if the wrong drive fails your lost.

-Which one will be more suitable for my use? i.e. nextcloud <-> smb archive storage (famliy photos etc.), iSCSI for hypervisor/vm's (running unifi controller, + game servers)

You have two different use cases for one box here. On the SMB/photo side, RAIDz2 will give better redundancy but on the other side you want IOPS for virtualization so striped mirrors would be best. This is similar to my use case(s) and I went with mirrors. I replicate to my old FreeNAS box for backups and thats RAIDz2. Just to be safe.

-what performance numbers would I be looking at for both raidz2 and mirror vdev over a 10gbe connection. A rough estimation is ok.

This can be tricky to answer. It can depend on how the hypervisor workloads use the ARC. Generally RAIDz2 will have more latency and overhead than mirrors. Mirrors, you can read from all disks at the same time, RAIDz2 will effectively be N-2 so with 4 disks you will only be able to read from 2 at a time.

 

[BloodyBonkers]

OK, I have decided that for now, the redundancy is the most important factor, so I will use Raidz2 and figure something out for the hypervisor storage as I go.

Just a quick side question. I read that zfs now has the ability to add disks without needing to create a new vdev (https://twitter.com/OpenZFS/status/921042446275944448). Is this available in FreeNAS yet?

 

[kdragon75]

OK, I have decided that for now, the redundancy is the most important factor, so I will use Raidz2 and figure something out for the hypervisor storage as I go.

Just a quick side question. I read that zfs now has the ability to add disks without needing to create a new vdev (https://twitter.com/OpenZFS/status/921042446275944448). Is this available in FreeNAS yet?

Well that's an up and coming feature that's not done and DEFINITELY not stable yet so no. Its not in FreeNAS, FreeBSD, or any non-tech preview release of ZFS. I do look forward to it though as it will include the same logic needed for rebalancing arrays with added vdevs too!