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Efficient Management of Backup Processes Using Amanda System at Purdue University

The Amanda backup system is designed to manage various standard backup programs rather than serving as a backup program itself. It optimizes the scheduling of backups with features like dump cycles, tape cycles, and estimated image sizes. The Amanda architecture includes planners, drivers, and dumper components that coordinate the backup process efficiently. This overview delves into managing backup queues, priority sorting, and strategies for generating and handling backups, ensuring a streamlined and effective data protection solution at Purdue University.

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Efficient Management of Backup Processes Using Amanda System at Purdue University

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  1. AMANDAUnder the Hood John R. Jackson Purdue University Computing Center jrj@purdue.edu

  2. Overview • Not a backup program itself • Manages other standard backup programs • System dump • GNU tar • smbtar • Optimized schedule • Dump cycle • Tape cycle • Estimated image sizes

  3. Overview(continued) tape driver planner driver taper driver dumper client holdingdisk sendsize sendbackup

  4. Planner • Get estimated image sizes • sendsize on client • Level 0 • Same level as last time • Next level • etimeout * number of disks • Analyze and pick initial level • Delay full dumps if total size too big • Promote full dumps if total size too small • Sort by “priority”, then size

  5. Strategy • standard • nofull • noinc • incronly • skip

  6. Driver • Gets sorted list from planner • Normal level • Degraded mode level • Starts one or more dumpers (inparallel) • Starts one taper

  7. Driver(continued) • Pick from beginning or end of queue? • Is it time to start this host? • Is it time to start this disk? • Is there enough bandwidth? • Is there enough holding disk space? • Is use of a holding disk allowed? • Are we below the client maxdumps limit? • Is this a different spindle?

  8. Dumper • Start sendbackup on client • Messages port • Data port (possibly encrypted) • Index port (optional) • Insert server side compression if requested • If “FILE-DUMP”: • Write tape header to holding disk chunk • Write data stream to holding disk chunk • Request new holding disk chunks from driver as needed • Else (“PORT-DUMP”): • Pass image to taper via localhost TCP connection

  9. Sendbackup msgs data index compression restoreprogram sendbackup stderr stdout backupprogram /dev/null stdin

  10. Taper • Run tape changer • Validate proper tape is mounted and rewrite label • Handle FILE-WRITE and PORT-WRITE commands • Write image to tape in 32 Kbyte chunks • Fail or advance to next tape on error

  11. Taper(continued) • Split into reader and writer • Shared memory buffer (e.g. 20 * 32 Kbytes) • Writer waits for all buffers full (or done) • Writer outputs as fast as possible for streaming • On error: • Advance to next tape if changer • Driver starts whole image over again

  12. Amandad • UDP for now • Client has no access to amanda.conf • Security checks • Run requested “service” • selfcheck • sendsize • sendbackup

  13. Files • Curinfo • Tapelist 200000525 B00116 reuse 200000524 B00115 reuse … • log.<YYYYMMDD>.<n> • Updated by driver, dumper and taper • Used by amreport to generate E-mail • amdump.<n> • detailed status • stdout/stderr from all programs • used by amstatus • /tmp/amanda/*.debug

  14. Administrative Tools • amcheck • amdump • amflush • amadmin • amstatus • amplot • amverify

  15. Administrative Tools(continued) • amtoc • amlabel • amrmtape • amtape • amcleanup • amreport

  16. Tape Format Label Tapemark Header Image Tapemark Header Image …

  17. Tape Format(continued) • No rewind!!! • System-V access method, not BSD • Tape label AMANDA: TAPESTART DATE 20000525 TAPE B00116 • Image header AMANDA: FILE 20000525 fortress.cc.purdue.edu / lev 1 comp N program /usr/sbin/ufsdump To restore, position tape at start of file and run: dd if=<tape> bs=32k skip=1 | /usr/sbin/ufsrestore –f… -

  18. Amrestore • Takes host, disk and datestamp patterns • Scans for all or first match • Usually gives back image ready for restore • Does not use any other AMANDA information

  19. Amrecover • Runs on client • Talks to amindexd on server to get file data • Talks to amidxtaped on tape host to read images • FTP-like interface and protocol

  20. Typical Problems • Check/Estimate/Data timeouts • Access not allowed • Host down • Disk offline • I/O error • port NN not secure • Broken pipe

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