thAttica, 5 century BCE.
No more than once a year,and only if the Assembly so decided,the citizens of Athens would gatheron Pnyx hill for a peculia...
Everyone had the optionof writing the nameof one fellow citizenon a shard of pottery or earthenware.
The shards were counted,and whoever received the most voteshad to leave the cityand was barred from returningfor 10 years ...
In Solonian democracy,the process was believed to havea cleansing effect on societyby removing those who misbehaved.
It was known as “ostrakismos”(οστρακισμός), the root ofthe modern English word ostracism.In High-Availability clustering,w...
Fencing:Putting things into a known state
WTF?         NFI...        ?        ?OK...       RTFM!
Better.                  Much. Tea, anyone?       Totally.                ?                ?                    Meh...
How can we fence?
Power fencing
?   bbl!?
Fabric fencing
??   ugh.
Who fences? Callers
fencedstonithd
What fences? Agents
IPMI       DRAC          iLO          RSASwitched PDU     Meatware
Why is this important?
Storage Access
Locking
Stop Failure
What can go wrong?
After 10 years,the banished personwas allowed to return.His exile carried no stigma.
Rejoining
mkelly@iplink.netflorian@hastexo.com
https://alteeve.comhttp://www.hastexo.com/shoutbox
Photo credits:        nath&mag       bazylek100         TitanasKostas Gerontis (Kokotron)
Fencing and Maintaining Sanity in High Availability Clusters
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Fencing and Maintaining Sanity in High Availability Clusters

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Talk presented by Florian Haas and Madison Kelly at LinuxCon Europe 2011, Prague, Czech Republic.

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Fencing and Maintaining Sanity in High Availability Clusters

  1. 1. thAttica, 5 century BCE.
  2. 2. No more than once a year,and only if the Assembly so decided,the citizens of Athens would gatheron Pnyx hill for a peculiar event.
  3. 3. Everyone had the optionof writing the nameof one fellow citizenon a shard of pottery or earthenware.
  4. 4. The shards were counted,and whoever received the most voteshad to leave the cityand was barred from returningfor 10 years unless recalled.
  5. 5. In Solonian democracy,the process was believed to havea cleansing effect on societyby removing those who misbehaved.
  6. 6. It was known as “ostrakismos”(οστρακισμός), the root ofthe modern English word ostracism.In High-Availability clustering,we call it fencing.
  7. 7. Fencing:Putting things into a known state
  8. 8. WTF? NFI... ? ?OK... RTFM!
  9. 9. Better. Much. Tea, anyone? Totally. ? ? Meh...
  10. 10. How can we fence?
  11. 11. Power fencing
  12. 12. ? bbl!?
  13. 13. Fabric fencing
  14. 14. ?? ugh.
  15. 15. Who fences? Callers
  16. 16. fencedstonithd
  17. 17. What fences? Agents
  18. 18. IPMI DRAC iLO RSASwitched PDU Meatware
  19. 19. Why is this important?
  20. 20. Storage Access
  21. 21. Locking
  22. 22. Stop Failure
  23. 23. What can go wrong?
  24. 24. After 10 years,the banished personwas allowed to return.His exile carried no stigma.
  25. 25. Rejoining
  26. 26. mkelly@iplink.netflorian@hastexo.com
  27. 27. https://alteeve.comhttp://www.hastexo.com/shoutbox
  28. 28. Photo credits: nath&mag bazylek100 TitanasKostas Gerontis (Kokotron)

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