topic Re: Dual controller - Active/Passive in ONTAP Hardware

Dual controller - Active/Passive

magnus_emmoth — Thu, 05 Jun 2025 07:07:37 GMT

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

aborzenkov — Fri, 01 Oct 2010 13:20:44 GMT

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

magnus_emmoth — Fri, 01 Oct 2010 13:22:43 GMT

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

Magnus

Re: Dual controller - Active/Passive

aborzenkov — Fri, 01 Oct 2010 13:25:14 GMT

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

Re: Dual controller - Active/Passive

alli — Fri, 01 Oct 2010 13:49:53 GMT

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

aborzenkov — Fri, 01 Oct 2010 14:02:44 GMT

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

alli — Fri, 01 Oct 2010 17:40:33 GMT

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

kevingolding — Sat, 02 Oct 2010 17:17:40 GMT

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

scottgelb — Sat, 02 Oct 2010 17:40:39 GMT

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

cdubart_c — Sun, 03 Oct 2010 19:55:04 GMT

minimum is 2 disks

Re: Dual controller - Active/Passive

GregKorten — Mon, 10 Jan 2011 07:37:58 GMT

What is the big concern about not having a hotspare if the Cluster node is used for Failover only, Active / "Passive"? I would not put any user data on the passive side and could even snapmirror the root volume to the Active controller or do an NDMP backup.

Even if the Passive node shuts down one would only then be exposed to a panic or someother really bad event on the "Active" Side during that outage. This seem like a pretty low risk.

It would be nice if Netapp gave you an option to run Ontap off of an SD Card or a USB drive... and let allthe Disks belong to the Active Node. I run production vShpere 4i servers installed on USB drives an SD cards why not Ontap?

Re: Dual controller - Active/Passive

mlorente1 — Mon, 26 Sep 2011 18:56:45 GMT

Hello everyone, hope you can resolve my doubts. Just bought a FAS 2040C, which has 2 controller active / active. The filer comes with 6 disks in the chassis and by default 3 disks have been distributed to each controller. My intention is to use the 6 disks on a controller, leaving the other without discs, so that would be turn off until a few months, when I connect to an expansion unit by FC.

The question is whether eliminating the aggregated that contains the root volume, Ii will be able to release the disks to assign them to the other controller, and do not know if I am destroying vital information on the second controller to activate it in next months. By eliminating the root volume, I guess I'm destroying the SO (DataOntap). Am I right?, How should proceed?

Thanks in advance.