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iofailuresim

Simulator of hard resets and fsync failures for applications that write append-only files. Assumes the application uses the C standard library's write(), fdatasync(), and fsync() for writing and syncing data.

Compile

gcc -std=c99 -fPIC -shared -o libiofailuresim.so iofailuresim.c -ldl

Run

LD_PRELOAD=./libiofailuresim.so <your application>

Configure

  • CRASH_FAILURE_ONE_IN=<n>: During a sync operation, crash the process immediately with a probability of 1/n. All unsynced writes are lost since they are buffered in process memory.
  • SYNC_FAILURE_ONE_IN=<n>: A sync operation will return failure with a probability of 1/n. All unsynced writes for the file are dropped to simulate the failure.
  • CRASH_AFTER_SYNC_FAILURE=<0|1>: If set to one, the program will kill itself some time after the first simulated sync failure. It does not happen immediately to allow the system to get itself into a weird state in case it doesn't handle sync failures properly.