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18 Dell EMC SC Series: Disaster Recovery for Microsoft SQL Server Using VMware Site Recovery Manager | CML1018
4.3 Configuring Dell Storage Manager
Dell Storage Manager is a required component for SRM. It must be up and available in the recovery site in
order for SRM to be able to carry out the automated failover workflow when the primary site goes down. In an
active/active site configuration, a DSM Data Collector is required at both sites, with the primary Data Collector
in one site and a remote Data Collector in the other. The primary or remote Data Collector can be at either
site. In the interest of application locale and responsiveness, it is recommended to have the primary Data
Collector at the location where the majority of the SC Series administration is performed.
DSM also contains a configuration setting that controls how SRM recovers volumes. This setting can be
configured using the DSM client. Volumes can be recovered by either using the active snapshot or the latest
frozen snapshot. To modify this setting, do the following:
1. Start the DSM client.
2. In the top-right area of the screen, click Edit Data Collector Settings.
3. On the left side of the Edit Data Collector Settings box, click Replication Settings.
4. Below VMware SRM Settings, there is a drop-down list for SRM Selectable Snapshot. Select one
of the following options:
- Always use Active Snapshot (default): Volumes will be recovered using the active snapshot.
- Use Active Snapshot if Replicating Active Snapshot: Volumes will be recovered using the
active snapshot if replication is configured to replicate the active snapshot. If the active snapshot
is not being replicated, the latest frozen snapshot is used.
- Always use Last Frozen Snapshot: Volumes will always be recovered using the latest frozen
snapshot, even if the active snapshot is being replicated.
- Use Restore Point Settings: Volumes will be recovered using the method defined in the restore
point. For example, this option would allow database volumes to be recovered using the latest
frozen snapshot, and all other volumes using the active snapshot.
5. Click OK.
Note that this setting will be ignored in the following scenarios where the most current data is replicated as
part of the recovery plan workflow:
• When performing a planned migration
• When performing a disaster recovery while the primary site is up
• When performing a test recovery when the Replicate recent changes to recovery site option is
selected
4.4 Configuring recovery in SRM
When recovering virtual machines running SQL Server, it is critical to understand the implications of the two
methods that SRM can use to recover volumes. SRM can either use the active snapshot or the latest frozen
snapshot when recovering volumes. If SQL Server databases cannot be recovered from the volumes created
by SRM, manual intervention will be required to successfully complete the recovery.
4.4.1 Recovery from the active snapshot
Recovering from the active snapshot can provide the lowest RPO, as it will contain the latest view of the
volume at the target site. For volumes using synchronous replication, this is the recommended recovery
method. When using asynchronous replication, recovering volumes from the active snapshot is not always
reliable. If SRM recovery fails using the active snapshot, the recovery will need to be completed manually