Preferred Practices For Deploying An Ha Pair - IBM N Series Hardware Manual

They own their spare disks, spare array LUNs, or both, and do not share them with the
other node.
They each have mailbox disks or array LUNs on the root volume:
– Two if it is an N series controller system (four if the root volume is mirrored by using the
SyncMirror feature).
– One if it is an N series gateway system (two if the root volume is mirrored by using the
SyncMirror feature).
They can be on the same Windows domain, or on separate domains.

7.1.3 Preferred practices for deploying an HA pair

To ensure that your HA pair is robust and operational, you need to be familiar the following
guidelines:
Make sure that the controllers and disk shelves are on separate power supplies or grids so
that a single power outage does not affect both components.
Use VIFs (virtual interfaces) to provide redundancy and improve availability of network
communication.
Maintain consistent configuration between the two nodes. An inconsistent configuration is
often the cause of failover problems.
Make sure that each node has sufficient resources to adequately support the workload of
both nodes during takeover mode.
Use the HA Configuration Checker to help ensure that failovers are successful.
If your system supports remote management (by using an Remote LAN Management
(RLM) or Service Processor), ensure that you configure it properly.
Higher numbers of traditional volumes and FlexVols on your system can affect takeover
and giveback times.
When adding traditional or FlexVols to an HA pair, consider testing the takeover and
giveback times to ensure that they fall within your requirements.
For systems that use disks, check for and remove any failed disks.
For more information about configuring an HA pair, see the Data ONTAP 8.0 7-Mode
High-Availability Configuration Guide found at:
http://www.ibm.com/storage/support/nas
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IBM System Storage N series Hardware Guide
Clarification: Disk ownership is established by Data ONTAP or the administrator,
rather than by which disk shelf the disk is attached to.
Tip: The mailbox disks or LUNs are used to do the following tasks:
Maintain consistency between the pair
Continually check whether the other node is running or whether it has run a
takeover
Store configuration information that is not specific to any particular node