Server Locality

Server Locality is a feature in SANsymphony that introduces the concept of associating SANsymphony servers with specific physical or logical locations, known as "localities." This addition helps improve the resilience of storage systems by allowing storage administrators to manage the placement of mirrored virtual disks (vDisks) across different impact zones. The primary objective is to enhance High Availability (HA) and disaster recovery capabilities by ensuring that mirrored virtual disks are spread across distinct locations. Server Locality enables users to recognize the location of each server in the system.

Server Locality supports 3-way mirroring assignments, where the ideal scenario is having mirrors placed across three distinct locations. The system will recognize the "quality" of the mirror configuration based on the number of different locations used. For example:

  • 3-way mirror in one location: Low quality (not resilient to local failures)

  • 3-way mirror in two locations: Better (resilient to one location failure)

  • 3-way mirror in three locations: Best (resilient to failures across two locations)

SANsymphony servers can be reassigned to existing localities. However, a server can only belong to one locality at a time. Also, a locality can only be deleted if no servers are assigned to it, ensuring that active localities are always accounted for in HA configurations.

Create and assign server locality for all servers before enabling Cyber Resiliency Mode for a server group. This will only be necessary when upgrading from an older PSP version to the DataCore SANsymphony 10.0 PSP19 or higher as the older versions did not have server locality or were not configured. On a new installation of DataCore SANsymphony PSP19 or higher, the system automatically creates and assigns a default server locality for each server. Users can also create additional localities and the locality of each server can be changed as necessary.

Server Group Locality

The Server Group Details page includes a Default Server Locality, which is set to the server group by default.

To modify the default server locality:

  1. Click Edit.
  2. Select the desired locality from the dropdown menu.
  3. Click Done.

Creating a Server Locality

Follow the below steps to easily create new server localities in SANsymphony:

  1. Navigate to Server Locality in the Home tab.

  2. Click Create Server Locality.

  3. Enter the desired name and description for the locality.

  4. Click Create.

Editing an Existing Server Locality

To edit an existing server locality:

  1. Select the locality.

  2. Click Edit.

  3. Change the name and description for the locality.

  4. Click Done.

Assigning/Setting a Server Locality

In the DataCore Server page, the default locality will be displayed below the name of the server.

When a new server is added to a server group, it is assigned the default server locality. To assign a server locality to a DataCore server:

  1. Navigate to the DataCore Server.

  2. Click Edit.

  3. Select the server locality from the dropdown.

  4. Click Done.

The Cyber Resiliency Rating is influenced by how your mirrored virtual disks are distributed across different locations.

A Best practice is to avoid placing all mirrors within the same locality. Spreading mirrors across multiple localities ensures that the storage system remains functional even if a failure occurs in one location.

Since the Cyber Resiliency Rating depends on the server's locality, ensuring that localities are properly configured is crucial. A well-designed locality setup helps mitigate the risks associated with single-point failures and improves the overall resilience of the storage system against cyber threats and disasters.