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SQLBits 2008 - SQL Server High Availability and Disaster Recovery Overview - charley hanania
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SQLBits 2008 - SQL Server High Availability and Disaster Recovery Overview - charley hanania

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Session from SQLBits 2008, covering: ...

Session from SQLBits 2008, covering:
Scopes of Protection in SQL Server 2005
SQL Server Backup Features and Technologies
SQL Server Disaster Recovery Features
SQL Server High Availability Features
SQL Server Data Distribution Features
Recoverability Scenarios Review

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SQLBits 2008 - SQL Server High Availability and Disaster Recovery Overview - charley hanania SQLBits 2008 - SQL Server High Availability and Disaster Recovery Overview - charley hanania Presentation Transcript

  • 01 March 2008 | Birmingham, United Kingdom
  • 01 March 2008 | Birmingham, United Kingdom HIGH AVAILABILITY AND DISASTER RECOVERY OVERVIEW Charley Hanania B.Sc (Computing Science), MCP, MCDBA, MCITP, MCTS, MCT Senior Database Specialist Production Product Owner – MS SQL Server UBS Investment Bank
  • 01 March 2008 | Birmingham, United Kingdom General Overview  Scopes of Protection in SQL Server 2005  SQL Server Backup Features and Technologies  SQL Server Disaster Recovery Features  SQL Server High Availability Features  SQL Server Data Distribution Features  Recoverability Scenarios Review
  • 01 March 2008 | Birmingham, United Kingdom Definitions  Scope of Protection  Object scope (or boundary) that can be protected from a recoverability or availability standpoint.  Disaster Recovery  Processes, policies and procedures of restoring operations critical to the resumption of business.  High Availability  The end users' ability to access the system. If a user cannot access the system, it is said to be unavailable.  Data Distribution  Creating subsets or copies of application data in different locations for system scalability, operational efficiency or manageability.  Outage / Downtime  Generally, the terms outage or downtime are used to refer to periods when a system is unavailable.
  • 01 March 2008 | Birmingham, United Kingdom Agenda  Scopes of Protection in SQL Server 2005  SQL Server Backup Features and Technologies  SQL Server Disaster Recovery Features  SQL Server High Availability Features  SQL Server Data Distribution Features  Recoverability Scenarios Review
  • 01 March 2008 | Birmingham, United Kingdom Scopes of Protection  Examples of scopes or conceptual objects  Database pages  Database objects (table, stored proc, function etc)  Files / Filegroups  Databases  Instances  Servers  Sites...  Others: ○ Transactions ○ Information consistency  data that is only meaningful when presented in a synchronised fashion with other data ○ User experience
  • 01 March 2008 | Birmingham, United Kingdom Protection: A Balancing Act... Balancing protection against cost and function is something you'll need to think about right from the start...  Key word: "Prioritise"  Decide what is important and what's nice to have  Look at costs ○ Time vs. component ○ Brand vs function ○ Consistency vs versatility ○ People vs automation ○ Technology vs manual processes ○ Etc  Look at effort ○ Homegrown vs prepackaged ○ Time to market/implementation timelines  Look at the return on the overall investment ○ Supportability ○ Fit For Use / Fit For Purpose
  • 01 March 2008 | Birmingham, United Kingdom Agenda  Scopes of Protection in SQL Server 2005  SQL Server Backup Features and Technologies  SQL Server Disaster Recovery Features  SQL Server High Availability Features  SQL Server Data Distribution Features  Recoverability Scenarios Review
  • 01 March 2008 | Birmingham, United Kingdom Backup  The underrated overachiever...  Recovery Models  Set the way that Transaction Logs are maintained.  Affect the restoration possibilities.  Not to be confused with Backup types!  The basis of any database recovery strategy.  3rd Party Vendors have tools which can extend backup and recovery possibilities.
  • 01 March 2008 | Birmingham, United Kingdom Recovery Models - Full  Enables recovery to the most atomic level  Point in time  Marked Transaction  Log Sequence Number (LSN)  Recovery of a corrupt page possible as well.  Transaction Logs must be backed up manually.  The backup will purge the inactive portion of the log after writing to disk
  • 01 March 2008 | Birmingham, United Kingdom Recovery Models – Bulk Logged  Designed for use with Full Recovery Model.  Allows bulk operations such as BCP and BULK INSERT to log less information to the Log.  Allows point in time recovery to the time that a Transaction Log backup occurred.  Should be switched on and off when needed, not used as a long term model.  Transaction Logs must be backed up manually.
  • 01 March 2008 | Birmingham, United Kingdom Recovery Models - Simple  No point in time (etc) recovery.  Automatically purges log periodically.  If the benefits of using log backups do not justify the cost of managing the backups, MS recommend that you use the simple recovery mode (Books Online)  Remember: entries are still written to the Log during normal operations!
  • 01 March 2008 | Birmingham, United Kingdom Backup Types - Full  Backs up complete database.  Objects, files and data.  Portion of Transaction Log as well.  Around the same size as the used space allocation.  Will allow recovery to the time that the backup finished.  Is the basis of all other backup types for a restore sequence.
  • 01 March 2008 | Birmingham, United Kingdom Backup Types – Differential  Uses a bitmap internally to work out what pages have changed in the database since the last full backup.  Generally much smaller that a full backup  Size depends on the number of unique pages changed.  When used with full and bulk-logged recovery model, can speed up point in time recovery.
  • 01 March 2008 | Birmingham, United Kingdom Backup Types – Transaction Log  Back up the sequence of changes that have been committed to the database since the last transaction log backup.  Allows for point in time (etc) recovery by reapplying the transactions in order to the point you want.  Needed for some of the DR solutions we’ll discuss.
  • 01 March 2008 | Birmingham, United Kingdom Backup Types – File/Filegroup  Needs a full backup to have been taken first.  Useful for databases that have multiple filegroups due to size of complexity of the system.  Is similar in concept to the differential backup, focussed on the files or filegroups within it.  Great way to save backup space and time during recovery.
  • 01 March 2008 | Birmingham, United Kingdom Fixing damaged pages using page restore
  • 01 March 2008 | Birmingham, United Kingdom Agenda  Scopes of Protection in SQL Server 2005  SQL Server Backup Features and Technologies  SQL Server Disaster Recovery Features  SQL Server High Availability Features  SQL Server Data Distribution Features  Recoverability Scenarios Review
  • 01 March 2008 | Birmingham, United Kingdom Disaster Recovery  All about the time and procedures needed to restore normal operations.  No “one” solution covers all bases  Combining solutions is possible  Think of overall system, not just the database.
  • 01 March 2008 | Birmingham, United Kingdom Log Shipping Concepts  Scope: Database  Primary  The copy of the database that the applications connect to.  Secondary  The copy of the primary database on another instance.  Can be use to offload reporting needs as a read only copy.  Database is inaccessible when being brought up to the Primary’s level.  Monitor  Optional SQL instance.  Backup failure alert information.  When the transaction log was last backed up.  When the transaction log was last copied and restored.
  • 01 March 2008 | Birmingham, United Kingdom Log Shipping - Method  Use a full backup to bring the secondary in synch with primary initially.  Do not recovery the db!  Three Steps:  Back up the Primary’s transaction log.  Copy the transaction log file to the secondary server instance.  Restore the log backup to the secondary.  Uses SQL Server Agent to do this work.
  • 01 March 2008 | Birmingham, United Kingdom Log Shipping Multiple Copies Trans scope maintained Manual Failover & reconfig No distance limits
  • 01 March 2008 | Birmingham, United Kingdom Database Mirroring Concepts  Principal  The copy of the database that the applications connect to.  The server that hosts it is known as the principal server.  Mirror  The copy of the principal database.  always in a restoring state;  not accessible to the applications.  The server that hosts the mirror database is known as the mirror server.  Witness  Optional SQL instance.  Separate from the principal and mirror instances.  When used in synchronous mode, provides automatic failover.
  • 01 March 2008 | Birmingham, United Kingdom Database Mirroring Concepts  Send Queue  Located at the Principle  Used if the log records can’t be sent at the rate at which they are generated.  It exists entirely in the transaction log.  Redo Queue  Located at the mirror  Used if the log records can’t be applied at the rate at which they are received.  Does not use extra storage or memory.  Exists entirely in the transaction log of the mirror.  It is the part of the hardened log that remains to be applied to the mirror database to roll it forward.
  • 01 March 2008 | Birmingham, United Kingdom Database Mirroring Concepts  Endpoint  SQL Server object that enables SQL Server to communicate over the network.  It encapsulates a transport protocol and a port number.  Failover  When the principal database (or the server hosting it) fails
  • 01 March 2008 | Birmingham, United Kingdom Database Mirroring Less than three seconds Zero committed work lost Maximum one mirror per DB Transparent client redirect
  • 01 March 2008 | Birmingham, United Kingdom Mirroring with Failover (Process) Clients Principal Server Mirror Server Witness Server
  • 01 March 2008 | Birmingham, United Kingdom Mirroring with Failover (Process) Clients Witness Server Mirror Server Principal Server
  • 01 March 2008 | Birmingham, United Kingdom Mirroring with Failover (Process) Clients Witness Server Mirror Server Principal Server
  • 01 March 2008 | Birmingham, United Kingdom Database Snapshots Historical data snapshots Safeguards against user / admin error Doesn’t protect against disk errors / other corruptions
  • 01 March 2008 | Birmingham, United Kingdom Database Snapshot Scenarios Mirroring for reporting Point-in-time reporting Recover from administrative error Protection from application or user error
  • 01 March 2008 | Birmingham, United Kingdom Agenda  Scopes of Protection in SQL Server 2005  SQL Server Backup Features and Technologies  SQL Server Disaster Recovery Features  SQL Server High Availability Features  SQL Server Data Distribution Features  Recoverability Scenarios Review
  • 01 March 2008 | Birmingham, United Kingdom High Availability  Minimise the risk to the organisation of H/W and S/W failures  Try to minimise the downtime (perceived downtime)  Each H/A solution caters for different risks  No “one” solution covers all bases  Combining solutions may be best approach  Careful planning/costing is advisable  Changes may be needed in your application  True H/A incorporates availability and performance models on all levels, business process, H/W, Application, N/W and service (employees)
  • 01 March 2008 | Birmingham, United Kingdom Clustering Concepts  Main Instance  Services the application.  Hot Standby Instance  Takes over database operations when the main server Instance fails.  Quorum  Tells the cluster which node should be active.  Intervenes when communications fail between nodes.  Failover  When the standby instance takes over from the main instance.
  • 01 March 2008 | Birmingham, United Kingdom ~20-second failover Eight nodes Zero committed work lost More SQL services supported Failover Clustering
  • 01 March 2008 | Birmingham, United Kingdom Implementing Failover Clustering Clustered Servers Virtual Instance Clients Heartbeat Network Shared Disk Array Private Network Effective but expensive
  • 01 March 2008 | Birmingham, United Kingdom Agenda  Scopes of Protection in SQL Server 2005  SQL Server Backup Features and Technologies  SQL Server Disaster Recovery Features  SQL Server High Availability Features  SQL Server Data Distribution Features  Recoverability Scenarios Review
  • 01 March 2008 | Birmingham, United Kingdom Replication Concepts  Publisher  “Publishes” to other locations through replication.  Many publications possible of logically related sets of objects and data.  Subscriber  Receives replicated data from one or more publishers and publications.  Depending on the type of replication, can also pass changes back or republish to other Subscribers.  Distributor  Stores replication specific data associated with one or more Publishers. ○ Replication status. ○ Publication Metadata. ○ Acts as a queue.  Publications and Articles  Comprised of many logically related articles (objects being replicated)
  • 01 March 2008 | Birmingham, United Kingdom Replication Provides hot standby No distance limits No conflict detection Single table to entire database Some committed data loss
  • 01 March 2008 | Birmingham, United Kingdom Fault Tolerance with Peer-to- Peer Los Angeles Zurich Sydney
  • 01 March 2008 | Birmingham, United Kingdom Load Balancing with Peer-to- Peer Read / Write Load Balancing Application Server Application Server Read-Only Load Balancing Replication Read Write Key
  • 01 March 2008 | Birmingham, United Kingdom Comparison of High Availability Options Feature Hot Standby Warm Standby Database Mirroring Failover Clustering Peer-to-Peer Transactional Replication Log Shipping Data Loss No data loss option No data loss Some Data Loss possible Some data loss possible Some data loss possible Automatic Failover Yes Yes Optional No No Transparent to Client Yes, Auto- Redirect Yes, Reconnect to same IP Optional No, NLB helps No, NLB helps Downtime < 3 Seconds 20 Sec + DB Recovery None Seconds Seconds + DB Recovery Standby Read Access Continuously accessible Snapshot No Continuously accessible Continuously accessible Intermittently accessible Data Granularity Database Only All System and User Databases Table or View Table or View Database Only Masks Disk Failure Yes No, Shared Disk Yes Yes Yes Special Hardware Needed No, Dup. system needed Specialized Hardware from Cluster HCL No, Dup. system needed No, Dup. system needed No, Dup. system needed Complexity Medium Medium/High High High Medium Microsoft TechNet 2005
  • 01 March 2008 | Birmingham, United Kingdom 5 nines…  Measured Annually  Measured in 9’s (%)  99% = 3 days, 15 hrs & 40 minutes  99.9% = 8 hrs & 46 minutes  99.99% = 52 mins & 30 seconds  99.999% (5 nines!) = 5 mins & 15 seconds
  • 01 March 2008 | Birmingham, United Kingdom Recoverability Scenario Review  24x7 Customer facing web portal  Customers connecting globally  Order entry  Order tracking  1000’s transactions per hour  System must be available  Outages for ordering not acceptable  Tracking can endure 2-3 hrs outage Discuss...
  • 01 March 2008 | Birmingham, United Kingdom Recoverability Scenario Review  Internal line of business app  100’s of users  Management Reporting Critical  Employees find that screens freeze at times ○ Root found to be when mgt run reports  Small outages ok  Loss of data unacceptable.  Some paper trails exist but not always reliable Discuss...
  • 01 March 2008 | Birmingham, United Kingdom Recoverability Scenario Review  Credit Card Risk System  1,000,000’s of transactions per minute.  Analyses out of ordinary spend & approves or rejects.  Data comes from feeder systems updated in batches.  System unavailability poses risk as shops may decide to lodge manually. Discuss...
  • 01 March 2008 | Birmingham, United Kingdom Recoverability Scenario Review  Point of Sale system  Interfaces with Risk system.  Must guarantee that transactions are not lost if completed.  1,000,000’s of transactions per minute.  Outages OK, as manual methods possible.  Unavailability preferable to missing transactions. Discuss...
  • 01 March 2008 | Birmingham, United Kingdom Using piecemeal restore
  • 01 March 2008 | Birmingham, United Kingdom SQL DR Resources  Description of disaster recovery options for Microsoft SQL Server  http://support.microsoft.com/kb/822400  SQL Server Disaster Recovery and Availability (MSDN forums)  https://forums.microsoft.com/MSDN/ShowForum. aspx?ForumID=744&SiteID=1
  • 01 March 2008 | Birmingham, United Kingdom SQL HA Resources  SQL Server High Availability Site  http://www.microsoft.com/sql/technologies/highavailab ility/default.mspx  SQL Server Mission Critical High Availability  http://www.microsoft.com/technet/prodtechnol/sql/the mes/high-availability.mspx  Why Consider a Service-Oriented Database Architecture for Scalability and Availability  http://www.microsoft.com/sql/techinfo/whitepapers/wh y-soda.mspx
  • 01 March 2008 | Birmingham, United Kingdom Additional Resources  Books Online has a wealth of information! (Sept 07)  http://msdn2.microsoft.com/en-us/library/ms130214.aspx  Database Mirroring in SQL Server 2005  http://www.microsoft.com/technet/prodtechnol/sql/2005/db mirror.mspx  Always on Technologies  http://www.microsoft.com/sql/alwayson/default.mspx  Performing Piecemeal Restores  http://msdn2.microsoft.com/en-us/library/ms177425.aspx
  • 01 March 2008 | Birmingham, United Kingdom Resources - Webcasts
  • 01 March 2008 | Birmingham, United Kingdom Additional Resources - Virtual Labs
  • 01 March 2008 | Birmingham, United Kingdom Additional Resources - Virtual Machines
  • 01 March 2008 | Birmingham, United Kingdom Resources - Community  Swiss PASS Chapter  www.sqlpass-swiss.org  Swiss IT Pro User Group  www.swissitpro.ch  Monthly sessions in Zurich and Geneva
  • 01 March 2008 | Birmingham, United Kingdom European PASS Conference 2008 http://www.european-pass-conference.com/default.aspx
  • 01 March 2008 | Birmingham, United Kingdom Thank You