Appendix F - Configuring Stretched Cluster and Tiebreaker
146
7700 Flash Storage Platform Installation Guide 7.6.3.x
530-0267-00 Rev 02
Stretched cluster configurations need an external server or the Cloud to serve as the location for
the Tiebreaker utility, which manages the interpretation of site status and failover between the
stretched cluster sites. If a 7700 FSP Controller fails at either site, the 7700 FSP Controller at the
surviving site will take over storage services for the offline 7700 FSP Controller.
In this way, a properly configured stretched cluster environment contains redundant 7700 FSP
Controllers, southbound Fibre Channel switches, and storage shelves that provide you with
complete end-to-end storage services across both sites in which the storage cluster spans.
Note:
For specific details about stretched cluster connectivity, deployment, and best practices,
see the latest version
Concerto 7700 FSP Stretch Cluster Implementation and Best Practices
Guide
.
Stretched Cluster Prerequisites
This section describes the basic requirements that need to be in place to deploy the 7700 FSP as
a stretched cluster:
•
Storage and zoning requirements
•
Networking and Tiebreaker requirements
Storage and Zoning Requirements
A stretched cluster requires the following storage and zoning configuration:
1.
Each site where a 7700 FSP Controller is deployed requires access to a northbound storage
fabric, a southbound storage fabric, and at least one storage shelf.
Each 7700 FSP Controller mirrors application data on each LUN from the shelf at its local site
to the corresponding shelf at the remote site. In general, local applications will run at both sites
while either site is prepared to take over all traffic in the event of a failure at the other site.
2.
The Fibre Channel switches must have long-distance Inter-Switch Link (ISL) connections. The
7700 FSP Controller at each site must have southbound access to the storage shelves at the
remote site. This requires that the southbound initiator ports on each 7700 FSP Controller
(ports 100, 101, 104, and 105) must be included in Fibre Channel switch zones at the remote
site.
3.
Each site must have two 11GB storage pools created on the local shelf to be configured as
7700 FSP Controller Configuration Repositories (CRs). One of the 11GB storage pools is the
CR for the local 7700 FSP Controller, and the other 11GB storage pool is the CR for the
remote 7700 FSP Controller.
Each 7700 FSP Controller maintains a mirror of its own CR at the remote site. During failover,
the surviving 7700 FSP Controller takes control of the CR mirror at the remote site. See
Figure F.1 for an example of a best practice CR for a 7700 FSP stretched cluster, and for more
details, see the latest version
Concerto 7700 FSP Stretch Cluster Implementation and Best
Practices Guide
.
