Minimum amount of RAM with SSD L2ARC

[prescott]

Hello.

I would like an expert opinion on a minimum amount of RAM on raidz2 with 6x 4TB. I already got 32GB DDR3 ECC RAM alocated because it's bare-metal install, but I'm thinking on going on ESXi virtualized with that SATA controller and LAN adapter passthrough. I would like to know the absolute minimum amount of RAM with and without 128GB SSD L2ARC because I would like to run as much as possible VMs on it. I read that 1GB per 1TB is recommended, but can I go much lower? The CPU is very powerful and the disks are all WD Blacks. So performance should not be much worse because of less ARC in my opinion. Also, the FreeNAS server does not have more then 5 active samba users, few NFS shares for torrent clients and 5-10 iSCSI shares it will have for storing and running VMs.

Thank you and Best Regards

 

[cyberjock]

The "expert" opinion is not to virtualize FreeNAS at all...

http://forums.freenas.org/index.php...duction-as-a-virtual-machine.12484/#post58364

We do not condone, recommend, or even support running FreeNAS as a VM. You are totally on your own to solve(or not solve) your problems. We've seen so much data loss we can't in good conscience ever recommend it.

 

[jgreco]

Hello.

I would like an expert opinion on a minimum amount of RAM on raidz2 with 6x 4TB. I already got 32GB DDR3 ECC RAM alocated because it's bare-metal install, but I'm thinking on going on ESXi virtualized with that SATA controller and LAN adapter passthrough. I would like to know the absolute minimum amount of RAM with and without 128GB SSD L2ARC because I would like to run as much as possible VMs on it. I read that 1GB per 1TB is recommended, but can I go much lower? The CPU is very powerful and the disks are all WD Blacks. So performance should not be much worse because of less ARC in my opinion. Also, the FreeNAS server does not have more then 5 active samba users, few NFS shares for torrent clients and 5-10 iSCSI shares it will have for storing and running VMs.

Thank you and Best Regards

The absolute minimum for FreeNAS is 8GB regardless of use. When you introduce VM usage, you need to move up to mirrored vdevs instead of RAIDZ2 if you want reasonable pool performance. VM use also significantly increases the amount of RAM, double the normal rule of thumb seems to work out well. So for a pool of 3 vdevs of 4TB each, that's 12TB of storage and so you probably need 24GB of RAM to start with. If you want to retain the RAIDZ2, you will have a 16TB pool and therefore should have no less than 32GB RAM.