Database Mirroring Vs Log Shipping
Database Mirroring
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Log-shipping
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Database mirroring is functionality in the SQL Server engine
that reads from the transaction log and copies transactions from the
principal server instance to the mirror server instance. Database
mirroring can operate synchronously or asynchronously.
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Log shipping is based on SQL Server Agent jobs that
periodically take log backups of the primary database, copy the backup files
to one or more secondary server instances, and restore the backups into the
secondary database(s). Log shipping supports an unlimited number of
secondary’s for each primary database.
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Database mirroring can operate synchronously or
asynchronously. If configured to operate synchronously, the transaction on
the principal will not be committed until it is hardened to disk on the
mirror.
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Log shipping is always asynchrony. Log shipping totally
depends on the log backup and restore schedule
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Database mirroring supports only one mirror for each principal
database. That means DB mirroring is at database level
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Log-shipping can work on database and server level. You can
configure multiple databases in logshipping
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Data Transfer: Individual
T-Log records are transferred using TCP endpoints
Transactional Consistency: Only committed transactions are transferred Server Limitation: Can be applied to only one mirror server Failover: Automatic Failover Duration: Failover is fast, sometimes < 3 seconds but not more than 10 seconds Role Change: Role change is fully automatic Client Re-direction: Fully automatic as it uses .NET 2.0/.Net 3.0 |
With Log Shipping:
Data Transfer:
T-Logs are backed up and transferred to secondary server
Transactional Consistency:
All committed and un-committed are transferred
Server Limitation:
Can be applied to multiple stand-by servers
Failover: Manual
Failover Duration:
Can take more than 30 mins
Role Change:
Role change is manual
Client Re-direction:
Manual changes required
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Support only full recovery model
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Supports full and bulk-logged recovery model
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Mirror database is always in recovery mode. To read it you
have use database snapshot.
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You can use the stand-by option to read the database on
standby server
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Auto Page Recovery introduced with SQL SERVER 2008 so it will
recover the damaged pages.
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Not supported
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