1 / 81

Archiving & Restoring

Archiving & Restoring. John F. Miller III. TOC. Term & History Disaster Recovery Planning Backup & Restore Procedures Architecture (XPS differences) The grab bag. Terminology. Serial Backup Archives the entire system at a single point in time using only one data stream Parallel Backup

louis-durham
Télécharger la présentation

Archiving & Restoring

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Archiving & Restoring John F. Miller III

  2. TOC • Term & History • Disaster Recovery Planning • Backup & Restore Procedures • Architecture (XPS differences) • The grab bag

  3. Terminology • Serial Backup • Archives the entire system at a single point in time using only one data stream • Parallel Backup • Archives the requested dbspace one at a time to N data streams • External Backup • Allows a third party application to backup the database server while maintain logical consistency

  4. Terminology • Cold Restore • Restoring the server when the database engine is offline • Warm Restore • Restores of dbspaces which occur while the database engine is online • Mixed Restore • A cold restore of set dbspaces followed by a warm restore of other dbspaces

  5. Terminology • Imported Restore • Transferring an archive taken on one computer and restoring it on a second computer • Point-in-Time Restore • Restoring the entire system to a single point it time • Restartable Restore • Allows the DBA to pickup the restore from the failure point

  6. Early Backup and Restore History • 1.X Turbo • Only Quiescent mode archives • 4.X named OnLine for advanced archiving technology • 5.X same core technology • limitation revealed (scalability & extensibility)

  7. DSA Backup and Restore History • 6.0 new client/server model developed • 7.1 & 7.20 same core technology • 7.21 new client (onbar) • 7.3 server API re-write • 9.2 onbar usability features added

  8. Pre-DSA Archive Bad Grammar Archive • Archive Checkpoint (get timestamp) • Free extents recorded • Reserve pages saved • Chunks backed-up by ascending chunk number • Pages modified during archive are placed in physical log • tbtape routinely scans physical log for unarchived before-images • Pages placed directly to tape

  9. Pre-DSA Restore • Begins with OnLine off-line • Reads configuration file, matches params to config params of archive tape • Zero out logs (physical & logical) • Validate size of all chunks • Read tape, copying pages based on their address directly to disk

  10. DSA Archive ArchitectureMajor Differences • True client-server architecture • Archived pages logically grouped by dbspaces • Granularity of creations • Granularity of restores • Warm restores • Physical log pages kept in temp tables

  11. Server Algorithm ChangesGood Grammar Archive • List is made of all pages that should be archived • Cost vs Benefit • Before images are queued by the modifier • A new thread is responsible for the before image handling

  12. Disaster Recovery • Goals • Planning

  13. What is a Successful Recovery? • “Successful” recovery is defined by your business needs

  14. Goals For Recovery • Determine acceptable recovery time • How long can your business function without the data? • How long can your production system be down during a restore?

  15. Determine Acceptable Data Loss Type Time Quantity Distribution

  16. Recovery Strategy Plan Recovery Goals Tune the Strategy Select Tools Analyze/Test the Strategy Implement The Strategy

  17. Data Layout • Poor data layout can hurt BAR performance • Isolating the different types of data can facility restore priority • Example • 8 dbspaces each with 2 chunk, but one dbspace has 68 chunk

  18. Data Layout Examples • Important frequently modified in its own dbspaces • important data such as orders should dbspace_orders • dbspace containing zipcodes and other lightly modified data can be backed up with less frequency

  19. Right, Fast or Cheap? Choose Two!

  20. Backup Utilities ontape ON-Bar External Backup/Restore Fault Tolerance Mechanisms Mirroring High Availability Data Replication (HDR) Enterprise Data Replication (DR) Select Tools Load/Unload High Performance Loader (HPL) dbexport/dbimport dbschema SQL load/unload onload/onunload dbload Customer ESQL programs

  21. Ontape Backup Features • Backup at the Server level • Support for incremental backups • Manual or continuous logical log backup • Restore entire system or single dbspace • Backup is self describing

  22. On-Bar Backup Features • Parallel backup and restore • System and dbspace level backup and restore • Support for incremental backups • Manual or automatic backup of logical logs • Instance point-in time recovery • Open interface for communication with storage managers (XBSA)

  23. External Backup Features • EBR allows administrators to make a consistent copy of their dbspaces using external tools • Used with many 3rd party backup products • Allows for both cold and warm restores

  24. EBR - Examples • Planned uses: • File system snapshots • Breaking of mirrors • Third party “raw” backup • Basic Steps • Block coserver(s) at checkpoint • Backup dbspaces using third party tools • Unblock coserver(s)

  25. Restoring • Logical Logs required • Restore looks hung, nothings happening • Handling unanticipated problems

  26. Logical Logs Required for a Restore • Cold Parallel Restore • Starting log is the log that contains the begin of the oldest active transaction when the first archive checkpoint occurred • At least the logical log that contains the last archive checkpoint • Cold Whole System (Non-Parallel) • No logical logs required • Logs included with archive

  27. Logical Logs Required for a Restore • Warm Restore • Starting log is the log that contains the begin of the oldest active transaction when the first archive checkpoint • All logs to the current point in time • If you are using DR then you must include the replay point

  28. Example of Logical Logs Required for a Restore Log 10 Log 11 Log 12 Log 13 B B B Archive Checkpoint B Oldest Begin Work Logs Required Cold restore all Logs 10-12 Optional 13 Warm restore Logs 11-> No Optional Logs

  29. Restartable vs. Suspended Restored • Restartable Restore • When the database engine prematurely shuts down the engine may be restarted in recovery mode • Suspended Restore • When the archive client receives an error which is restartable and the database engine does not shutdown

  30. Restartable Restore • Turned OFF by default • What can restart when? • Whole system • Partial Restore • Logical Recovery from a cold restore • Only available with On-BAR • onbar -RESTART

  31. Architecture • Overview • Archive Clients • Moving Data • IDS • XPS • Server Threads • XPS Architecture

  32. What Pages are Sent to the Archive • If page’s timestamp is older than maxstamp and newer than minstamp, it is put to tape • If a page is greater than current stamp, but older than minstamp, it is put to tape, and it’s timestamp is updated to maxstamp-1 • Pages newer than max, but older than current are considered to be modified after the archive started, and are ignored.

  33. Understanding Timestamps 0 Max-Stamp Not Archived Current Stamp

  34. OnLine Wheel-O-Death 0 Min-Stamp Max-Stamp The timestamp 50% away from Max-Stamp ie Max-Stamp - 2GB The timestamp at the start of the archive Not Archived All Pages in the red region have their timestamp updated along with being archived Current Stamp The timestamp at the current point in time

  35. Archive Clients EBR SMV Onbar Common Archive Code XBSA XBSA Ontape

  36. DSA Client Server Model SQLI/ASF Network Connection Archive Client Archive BE Streams Local Connection

  37. Moving Data between Client and Server ONINIT SQLI Requests Archive Data Buffer SQLI Returns Shared Memory Address Archive Client Shared Memory

  38. Moving Data between Client/Server • The size of the buffers used to transmit data • ontape - control by onconfig’s TAPEBLOCK • onBar - BAR_XFER_BUFSIZE - maximum size is one online page smaller than 64kb • The number of buffers: • ontape • onbar - BAR_XPORT_COUNT min 3 max 99 • Monitoring the data transfer • onstat -g stq

  39. What Data is Shipped to the Archive Client • Server sends raw online pages just like they exist on disk

  40. Example of onstat -g stq Stream Queue: (session 11 cnt 10) 0:ad91400 1:ada1400 2:adb1400 3:adc1400 4:add1400 5:ade1400 6:adf1400 7:ae01400 8:ae11400 9:ae21400 Full Queue: (cnt 0 waiters 0) 0:0 1:ada1400 2:adb1400 3:adc1400 4:add1400 5:ade1400 6:adf1400 7:ae01400 8:ae11400 Empty Queue: (cnt 0 waiters 1) Stream Queue: (session 10 cnt 10) 0:ac8d400 1:ac9d400 2:acad400 3:acbd400 4:accd400 5:acdd400 6:aced400 7:acfd400 8:ad0d400 9:ad1d400 Full Queue: (cnt 9 waiters 0) 0:ac9d400 1:acad400 2:0 3:accd400 4:acdd400 5:aced400 6:acfd400 7:ad0d400 8:ad1d400 Empty Queue: (cnt 0 waiters 1)

  41. Server Threads • ontape • Scanner • Before Image Processor

  42. Ontape Thread • Always called ontape regardless of archive client • Responsible for all communication to archive client

  43. Scanner Thread (arc_backup1) • The “dummy” thread, geared for I/O performance and not thinking • Handed a list of pages to backup • Scans data from disk into shared memory buffers • Makes NO decisions about the data • Ensures the page address is correct

  44. Before Image Processor Thread (arc_backup2) • Monitors the before image queues • Determines if the before image needs to be saved or discarded • Drains the before image memory queue, by storing the page images into temp tables • Creates multiple temp tables if required

  45. XPS Difference & Architecture Overview • Basic XPS Architecture • Client Sub-Systems • Server Sub-Systems • Differences • sysutils • configuration

  46. Basic XPS Architecture Storage Manager 1 Coserver 4 Storage Manager 2 Coserver 3 OnLine XPS Coserver 2 Coserver 1 onbar

  47. Client Sub-Systems

  48. Client Sub-Systems Storage Manager 1 onbar_w Coserver 4 Coserver 3 OnLine XPS Coserver 2 Coserver 1 onbar onbar_d

  49. ASF/local streams Send/Receive commands and data buffers Backup Scheduler (BUS) distributes tasks to workers XBAR communicates between coservers RSAM only sees a single coserver manages all I/O to disk (dbspaces/chunks) Server Sub-Systems New New

  50. XBAR • Interfaces with both BUS and RSAM • Manages distributed execution of backup and restores • transfers data from the object’s coserver (coserver where the dbspace/chunk exists) to onbar_w’s coserver (output coserver) • Uses XMF between coservers • Uses local stream between onbar_w and output coserver

More Related