The FAS2040A (Dual Controller Model)
utilizes an Active-Active HA pair of controllers. Each controller
head must have disk ownership of the disks on which its own root
volume sits. In a fail-over situation, the remaining cluster head
will take over the 'virtual' identity of the failed head with its
igroups, LUN mappings, etcetera.
Out of the factory, the FAS2040A is
configured similarly to the diagram below:
Key:
A = Controller A
B = ControllerB
D = Data Disk
P = Parity Disk
dP = Double Parity Disk
S = Spare
X = Unowned
Only 2 of the available disks are
available for data (1 data disk per controller), and the available
data space also contains the root volume /vol/vol0
In the scenario where we have a
FAS2040A with 12 disks, and no available disk shelf, below are some
options available
Option 1: Utilizing Each Head
Equally
In the above option, we can either have
6 disks available for data (3 on each controller) if require to keep
a hot spare on each controller, or can have 8 disks available for
data (4 on each controller) if it is not required to keep a hot spare
on each controller.
Option 2: Going For As Large A
Volume As Possible
In the above option, we can have either
7 disks available for data (6 on one controller, 1 on the other) if
require to keep a hot spare with the main controllers pool of disks,
or can have 8 disks available for data (7 on one controller, 1 on the
other) if do not require to keep a hot spare with the main
controllers pool of disks.
Note 1: RAID-4 (which has only one
parity disk) is not considered here as it is not possible to disable
the alarm for no available spare if using RAID-4. Also, for doing no
disruptive disk firmware upgrades, need to be on RAID-DP, and it is
preferable to have a RAID-DP than a RAID-4 with hot spare.
Note 2: Ideally, keep at least one
hot spare. Data ONTAP has the intelligence to analyze a drive that
has been marked as failed, and if checks out okay will re-add it to
the spares pool.
Related Posts:
NetApp: FAS2040A Walkthrough Setup & Install Notes Part 1/5 – Introduction
Related Posts:
NetApp: FAS2040A Walkthrough Setup & Install Notes Part 1/5 – Introduction
Thank you for interesting article,
ReplyDeleteIs it possible to detail how to get from Factory setup to Option2? on FAS 2040 by default aggregate where root volume resides consists of tree disks that are odd numbered.How can I rearrange the underlying disks?
Hi Daugavpils,
ReplyDeleteI'd check out my post on the simulator:
http://cosonok.blogspot.co.uk/2011/12/netapp-simulator-81-walkthrough-setup.html
And also Julian Wood's (goes into reallocating disks):
http://www.wooditwork.com/2012/01/04/installing-maximising-the-netapp-ontap-8-1-simulator/
Cheers,
VCosonok