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A Comparison of VERITAS Replication Technologies

A Comparison of VERITAS Replication Technologies. Marty Ward Matt Fairbanks HanCheng Hsiung VERITAS Software. Database Replication Option. Marty Ward VERITAS Software mward@veritas.com. Goals. Without impacting performance, how can I: Backup my production server

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A Comparison of VERITAS Replication Technologies

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  1. A Comparison of VERITAS Replication Technologies Marty Ward Matt Fairbanks HanCheng Hsiung VERITAS Software

  2. Database Replication Option Marty Ward VERITAS Software mward@veritas.com

  3. Goals • Without impacting performance, how can I: • Backup my production server • Run ERP reports or Decision Support queries • Protect against corruption of my production database • Maintain multiple ONLINE versions of my database for near instant access • When my: • Production systems are overloaded • Operations are 24x7x365

  4. Database Replication Option • Point-in-time Replication • Uses Storage Checkpoints to Track Changed Blocks for Optimal Replication • Maintain Multiple Versions of Database Online for Near Instant Access • Each Storage Checkpoint Corresponds to a Version of the Database at a Point-in-time • Minimal Storage Required for the Changed Blocks

  5. Public Network Private Network Primary Server Secondary Server Applications • Backup/Restore • ERP Report Server • Recover from DB Corruption • Test System • Training System

  6. Public Network Private Network Primary Server Secondary Server A B D H Database Replication Option

  7. Benefit Summary • Saves time and money (less data to move over the network, less data to store on disk) • High Availability of Data • Secondary copies always online • Multiple copies available with minimal extra storage via Storage Checkpoints • Replicated Databases are always accessible Read/Write • Manageability • Can user over LAN or WAN • Customizable parameters

  8. Storage Replicator Matt Fairbanks VERITAS Software

  9. Effects of Disaster • Few organizations that sustain major data loss remain in business • World Trade Center bombing example • University of Texas study • Is your IT organization prepared for a site disaster? How much data would you lose? • Value of the data, not prices, drives storage decisions

  10. “Site” Failures • Power Outage • Broken Telecommunication Links • Natural Disasters • Flood, Hurricane, Tornado, Ice Storm, Earthquake, Fire, Chemical, etc... • Man-made Disasters • Act of War, Terrorism, Fire, Sabotage, etc...

  11. Real-time Replication • Two copies are better than one • Consistent image of application storage • Changes transmitted to secondary site in real time • Entire environment replicated • Foundation for Disaster Recovery

  12. Replication Modes SYNCHRONOUS ASYNCHRONOUS • Maximum data currency (up to date) • May have greater performance impact • Two phase commit across all nodes • Write commit latency across nodes • Maximum performance • Lower overhead than synchronous • Data on secondary may “get behind” • Uses logs to avoid two-phase commit and write latency

  13. Write Order Fidelity SYNCHRONOUS ASYNCHRONOUS Storage Replicator maintains write ordering for complete DATA INTEGRITY/CONSISTENCY at secondary

  14. Storage Replicator for Volume Manager (SRVM) • Block-level mirror of Primary data to Secondary • Synchronous or Async modes • Entire volume replication • Scalable to 32 sites • Storage hardware independent • Complete DBMS support • Part of VxVM (3.0.x) • Auto sync (over wire) • Log overflow protection • Solaris/HP-UX support

  15. Storage Replicator for Volume Manager (SRVM) • Data integrity always maintained at Secondary • Secondary sites may be behind (async) • Log queues write requests in case of • Insufficient network bandwidth • Network failure • Secondary failure • Information on Secondary is not available until promotion

  16. Disaster Recovery • Replicate critical information to a disaster-safe location • Replicate data over WAN • Current data at remote hot site • Replicate entire environment (not just logs) • Data ALWAYS consistent (integrity)

  17. Company A

  18. Company B

  19. GeoCluster WAN Wide Area Failover/Migration • Total solution based on VERITAS core technology • VM/SRVM, VCS, GeoCluster • Implements “Cluster of Clusters” • Single point of administration for multiple geographically distributed clusters

  20. Comparison of VERITAS Replication Technologies HanCheng Hsiung VERITAS hancheng@VERITAS.com

  21. Outline • Review VERITAS Replication Technologies • Disaster Recovery Solution Consideration • Using VERITAS Data Replication solutions for disaster recovery – Replicating the enterprise database • Comparison of the different VERITAS solutions

  22. VERITAS Replication Technologies • DRO (Database Replication Option) • SRVM (Storage Replicator for Volume Manager) • SRVM + DRO work together

  23. Primary Server Remote Replica Only Changed BlocksSince LastStorage Checkpoint Backup Request to replicate data DRO (Database Replication Option) • Delayed, On-demand based replication of only changed blocks. VERITAS File System with Storage Checkpoints

  24. DRO (Database Replication Option) • Storage Checkpoint • A persistent snapshot of all user files in a VxFS file system at a moment in time. • Track the changed file system blocks between two storage checkpoints • Replica System can be used for a variety of workload (Off-host processing) • Reporting, backup, and data mining • Replica system is always behind the Primary

  25. Primary Server Remote Replica Writes SRVM • Real-time disaster recovery solution • Replicate every write done to a volume to the remote replica system in real-time

  26. SRVM • Fast synchronous replication • One to many replication • Data writes to SRL (Storage Replicator Log) first • Secondary volumes cannot be used during the replication • Support asynchronous replication mode for less critical environment

  27. Disaster Recovery Solution Consideration • How to make up-to-date production data available in the secondary system • Cost to make data available in the secondary system • Time to re-start the production workload on the secondary system • Usability of the secondary system – can the secondary be used while it is standing by ?

  28. Primary Server Remote Replica Network SAP R/3 with Oracle In Solaris 2.6 Disaster Recovery using Data Replication Technologies for enterprise database • A study done in the following environment • Running SAP transactions from client workstation. Use SAP transaction va01 to generate 40,000 sales documents.

  29. Disaster Recovery using Data Replication Technologies for the enterprise database • Different VERITAS replication technologies are used: • SRVM – Replicate entire database instance • DRO + shipping Oracle Archived logs( via remote copy or NFS mounting etc.). Replication interval is set to 16 hours( the entire test time) • Using SRVM and DRO together

  30. Oracle Database Instance • Database Files • On-line redo logs • Control files • Archived logs ( off-line redo logs)

  31. Disaster Recovery using Data Replication Technologies for the enterprise database • Using SRVM and DRO together Copy the online redo logs and control file before the recover SRVM Online Redo logs, archived logs, and Oracle Control file A, C & R D D D A C R DRO Replication Data files Oracle instance D Primary Machine network Secondary Machine

  32. Data Transfer CostTotal Data Replicated during the Test Run • SRVM • 8.59GB (47% online redo logs, 23% archived logs, 28% data files, and 2% control files) • SRVM + DRO • 6.17 GB via SRVM (65% online redo logs, 32% archived logs, and 3% control files) • 351.15 MB via DRO ( all in data files ) • DRO • 351.15 MB via DRO ( all in data files ) • 1.91GB archived log files via remote copy

  33. Extra Disk writes on the Primary • SRVM • 8.59 GB writes to SRL(Storage Replicator Log) • DRO + SRVM • 6.17 GB writes to SRL • DRO • Small amount of data writes while creating storage checkpoints

  34. RecoverabilityHow up to date the data is • SRVM • Up-to-date recoverability • SRVM + DRO • Up-to-date recoverability • DRO • Transactions in the current redo logs will be lost. Transactions in any archived log not yet copy to secondary will be lost.

  35. Speed of Recovery • SRVM • Fast, the only time spent will be the time to mount and possible check all the file systems. Such time can be eliminated if using raw partitions. • SRVM + DRO • Depends on how many archived logs need to replay during the recovery time. The longer the replication interval is, the longer the recovery time will be. • DRO • The recovery time of DRO is similar to SRVM + DRO

  36. Usability of the Secondary system • SRVM • Cannot use the secondary volume directly • SRVM + DRO • Secondary database is always available except when the replication is in progress. • DRO • Secondary database is always available except when the replication is in progress.

  37. SummaryChoice an appropriate solution

  38. A Comparison of VERITAS Replication Technologies Questions?

  39. A Comparison of VERITAS Replication Technologies Thank You!

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