sql server 2008 r2 - implementing high availabilitty
Post on 13-May-2015
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SQL Server 2008 R2Implementing High Availability
High availability ChallengeUptime SLA Downtime Per
YearDowntime Per Month
99.9% 8.76 Hours 43.8 Minutes
99.99% 52.6 Minutes 4.38 Minutes
99.999% 5.26 Minutes 0.438 Minutes
SQL Server 2008 R2 High Availability Goals Hardware Failover Clustering Database Mirroring Replication Log Shipping
Goals for High Availability Second copy of our data Have Real time or Near Real time switch
over Second copy – Updated Frequently Reduce workload – Automatic Switch
over to the second database
Less downtime for our users
Techniques available Hardware Failover clustering Database Mirroring Replication Log Shipping
Hardware Redundant Power supplies RAID Arrays Redundant CPU Power Redundant Network Cards SCSI/SAN Controllers
Key is redundancy
Node A
SQL Server failover clustering
Node B
Nodes
Clients
H/W H/W
Active - Passive
SQL Server failover clustering
Nodes A
Clients
Node A
H/W
Node B
H/W
Active - Active
Nodes B
A
C
DB
SQL 1
SQL 2
SQL 3
SQL 4
SQL 5
SQL 6
SQL 7
SQL 8
SQL 1(Principal)
A
B
SQL 2(Mirror)
A(copy)Transaction
Clients
SQL Native Client
Database Mirroringo Hot Standby protects against database or server failureo Provides a fault-tolerant database o Cost effective as no specialized hardware is requiredo Straightforward setup and administrationo Automatic or manual failover
o SQL Server 2008 R2 does not require a database restart after manual failover
o No shared components; two separate copies of datao SQL Server 2008 compresses the log stream from
principal to mirror
Database Mirroring Several different modes available It works on per database, clustering is per
instance basis Interaction with other database features which
involve storage outside database Log shipping Full text catalogues Database snapshots Replication
Does not support FILESTREAM Need to create server logins
Replication
Transactional Merge Replication Snapshot Replication
There is no built in type of Failover
A
C
B
Tokyo
New Delhi
New York
Clients
Replication High performance ─ latency measured in
seconds Minimal load on the server Cost effective as no specialized
hardware is required Straightforward setup and
administration Subscriber is accessible Used mainly for Scalability
SQL 1
A
B
SQL 2
A(copy)
Transaction Log Backup
Transaction Log Backup
Clients
Log Shipping Not Real-time Less Resource Hungary on Servers Supports FILESTREAM Provides database redundancy
Every some [Time]
Filestream
Log Shipping Cost effective as no specialized
hardware is required Straightforward setup and
administration Running read operations
such as reports on asecondary server is permitted
Users are disconnected when logrestore occurs
Log Shipping Can maintain multiple secondary servers Records history and status of backup/restore
jobs May set up to raise alerts when jobs fail
SQL Server 2008 R2 High Availability Goals Hardware Failover Clustering Database Mirroring Replication Log Shipping
Thank you and Q.A.
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