What are the top SQL Server Disaster Recovery Solutions ?
SQL Server is an enterprise solution which provides various solution to cover DR scenarios. A disaster recovery includes money and solution depends on how much money you want to spend on DR solution. Here is list of solutions, which range from few $$$ to million dollar solutions.

Solution 1 – SQL Server HADR 
“HADR” is a high-availability and disaster recovery solution introduced in SQL Server 2012. This is the only solution which provides both high availability  as well as data recovery in case of a disaster on any nature.

PROS

• Multi-Database Failover
• Multiple Secondary’s
• Active Secondary’s
• Fast Client Connection Redirection
• Windows Server Core
• Multisite Clustering

CONS

• Expensive Solution
• Complicated / Complex Environment
• Woks only with SQL Server 2012 and Window Server 2008 onward only

If you want get answer, “How to Implement HADR”, please check my previous post, “How to Implement HADR – Step by Step Guide with screenshots”

Solution 2 – SQL Server Clustering
This is one of the best High Availability industry proven Solution. As part of this solution, be bind SQL Services with two Physical Servers which shares the common storage in such a way that SQL Services will automatically failover to other available node if a hardware failure or a software failure occurs on first node.


PROS

• HIGH availability solution as Services were always available
• Supported by all versions of SQL Server starting from SQL Server
• Automatic Failover
• No loss of Data
• Coupled with SAN as shared array for storage

CONS

• This is not a DR solution - Clustering doesn’t cover disk array (Storage) failure as all clustered nodes shares the same storage.
• Restricted to use local subnet only ** This restriction is removed in Windows Server 2008 onwards.
• High COST as identical hardware, shared storage is required
• Failover clustering does not allow you to create failover clusters at the database level or at the database object level, such as the table level.

If you want get answer, “What is Clustering”, “Installing Windows 2008 clustered environment”, “
How to Install SQL Server clustered instance” 

Solution 3 – Database Mirroring
Database mirroring is an alternative high-availability solution and it also offers DR also. Database mirroring supports automatic failover, but does not require cluster-capable hardware, and can therefore provide a cost-effective alternative to failover clustering.
In a database mirroring solution, a database is stored on one server and copied to another, providing a standby copy of the database that can service clients in the event of a server failure

PROS

• Increases data protection.
• Increases availability of a database.
• Improves the availability of the production database during upgrades.
• Solution at Granular level instead of Server level this solution works ate database level.
• can be used as a DR solution too

CONS

• Standby copy (Mirrored) can not be used, it’s just a stand by
• Database mirroring is limited to only two servers
• Database mirroring is limited to only 10 database per servers
• Need to configure your DSN string to have both mirrored servers in it so that when they switch you notice nothing- In case of Clustering and HADR, this is not required
• Partners must use the same edition.
• Asynchronous database mirroring (high-performance mode) is supported only by Enterprise Edition
• Can not be used for system databases like master, msdb, model databases.

If you want get answer, “How to Set up Database Mirroring in SQL Server 2008”,please check my video tutorial “How to Set up Database Mirroring in SQL Server 2008 (Video)”

Solution 4 – Log Shipping

Log shipping is primarily a failover solution. As part of this solution, log shipping provides database-level redundancy for SQL Server database by automatically backing up, copying, and restoring transaction logs on standby servers

PROS

• Standby databases can be available for read-only queries.
• Multiple standby servers can be configured

CONS

• Possible data loss when the primary server fails
• Manual Failover, there is no automatic failover
• Purely works on LSN, If case database log is truncated by some one, then need to again copy entire database.

Solution 5 – Replication
Replication is the mechanism for creating and maintaining multiple copies of the same data. Replication allows,
• Multiple copies of data can be kept in sync.
• Allows data be closer to users, improving performance.
• Allows a branch office to work when not connected to the main office.
• Separate process and offload work from production servers
PROS

• Work at Granular level, Can set replication for a specific table, set of tables, or subset of data within a table or tables on one or many other servers.

CONS

• Need more DBA efforts to manage replication
• need to manual failover
• can loose data

If you want to know, “What are the type of replication available in SQL Server”or “How to set up Replication“, Video Tutorial, check my previous post, “Replication with SQL Server 2008”

Solution 6 – Native SQL BACKUPS
This is the most basic form of disaster recovery for SQL Server and one that was being practiced in every situation.