Bad idea using FreeNAS for 2012 VM host?

[ibrouting]

I have a FreeNAS server I have been running since version 7 and love it. I use it with Duplicati to backup about 45 local and remote machines via SSH and it just....works. We just received in a 2012 R2 Datacenter server that the server guys wanted, but it only has 2 148GB drives (with 128GB of RAM, go figure). So the question came up if they can store the VM's on FreeNAS (I have about 16TB free). Is this a good idea or a BAD IDEA. If it works, they would store and load the VM from FreeNAS and just use the server as a head end. Since I have never tried to host a VM (or even a CIFS share) I just wanted to ask for an opinion from those that may have been down this road.

 

[SweetAndLow]

Do these vms need to perform fast? If they do you will need mirrored vdevs, lots of memory and maybe even a l2arc device.

Yes VM storage will work but getting high performance is harder.

 

[ibrouting]

Do these vms need to perform fast? If they do you will need mirrored vdevs, lots of memory and maybe even a l2arc device.

Yes VM storage will work but getting high performance is harder.

Thank you for the prompt reply! No, the machines would be email, a linux web server for an Intranet portal (60 users max and never more than 5 at a time) and a SQL server that runs a pretty much stagnant pool of data. Is this best to do with a CIFS share or iSCSI or???

 

[SweetAndLow]

Mail server and SQL server sound like higher performance to me. If you share with iscsi you shouldn't allow your pool to become more than 60% full otherwise your will see massive performance drop off.

 

[cyberjock]

Yeah.. that sounds like "high demand" if you want to run a mail server and SQL server. Both of those put some hurt on a ZFS based system. :P

 

[Nick2253]

In a standard configuration, I would say it's a bad idea. In particular, pulling data from FreeNAS will be terrible for random I/O, which is what their email and SQL databases will be doing constantly.

Depending what the budget is, I would pick on of three options:

1. You can mitigate the speed problems with lots of RAM and a high-speed SLOG. Exactly how much RAM depends on the use case, but more is generally better than less :D
2. Get some high performance SAS drives, and put those in a new striped-mirrored pool, and provide that for the VMs. The speed of the SAS drives, plus the striped mirrors, will give you some improved performance. I would still strongly recommend a SLOG.
3. However, I'd say that the best approach would be to simply get some larger drives for the server and set them in a mirror. If the server can hold four drives, then a local RAID10 array will give you very good performance, even with slower drives (like NAS drives).

Don't forget to ensure that you have sync writes enables. I don't remember if it's enabled by default over iSCSI. If it's not enabled, there's a serious risk that you'll lose or corrupt data for the VMs. (https://forums.freenas.org/index.ph...xi-nfs-so-slow-and-why-is-iscsi-faster.12506/)