Subscribe
Accepted Solution

Dual controller - Active/Passive

Hi,

How do I configure a FAS2020 with dual controller to be setup with active/passive?

Also, I would like to assign all the disks to one of the controllers, leaving the other one without any.

Is this possible?

Magnus

Re: Dual controller - Active/Passive

To have automatic failover between controllers both must be up and running. To run controller needs to have at least root volume – i.e. disks. So if you assign all disks to one controller second won’t run and you will lose redundancy – i.e. controller failover, possibility to do NDU.

Re: Dual controller - Active/Passive

What is the minimum number of disks that must be assigned to the second controller?

Magnus

Re: Dual controller - Active/Passive

The absolute minimum is 2 disks. I have customer who runs FAS2070 for 5 years in this configuration ☺

Re: Dual controller - Active/Passive

To clarify,

The minimum number to assign to the secondary controller is 2 plus 1 spare = so actually 3! This is a RAID4 configuration...1 parity + 1 data + 1 spare.

Re: Dual controller - Active/Passive

No. The absolute minimum is 2. You do not need spare to run controller. As I already told, I have customers who have been running this way for years.

I do not recommend it, but it is doable.

Re: Dual controller - Active/Passive

You don't need a spare to run the controller, that's correct...but this is the opposite of NetApp's best practices. What happens when you loose a drive on a 2 disk raid4? What did you do about the endless messages that pop up about not having a spare available? "I do not recommend it, but it is doable" should have been the first piece of advice given if you're leading someone down the wrong path to start.

Re: Dual controller - Active/Passive

raid 4 has other issues in regards to performing NDU's also, makes it a pain when you want to upgrade to a later version of ONTAP...

personally, I'd use three disks in an aggregate, don't use a spare (unless a fourth disks was available, defo recomended to have a spare) and the turn the raid.min_spares option (or something like that) to 0 to stop the messages...

Re: Dual controller - Active/Passive

Another consideration is raid.timeout.  When there is a disk failure, and there is no spare available (or if the nvram battery fails), raid.timeout (default = 24 hours) goes into effect and the system will shutdown.  You can modify this option or replace the failed disk with spare before the timeout (assuming not a weekend with no one around) but not best practice as mentioned earlier.  Also, rapid raid recovery and maintenance garage are not available with no spares.  If a passive node less of an issue, but maybe go to the pencil fund and buy an extra disk drive

Re: Dual controller - Active/Passive

minimum is 2 disks