Major - P3 format tried to drop checkpoints during a hot backup: this is likely a failure in the format test program, it's not supposed to do anything that would delete checkpoints during a hot backup, and that code recently changed in WT-3582.
http://build.wiredtiger.com:8080/job/wiredtiger-test-format-stress-sanitizer-ppc/3671/
WT_SESSION.checkpoint: checkpoint mine.3 blocked by hot backup: it would delete an existing checkpoint, and checkpoints cannot be deleted during a hot backup: Device or resource busy
Here's the CONFIG:
############################################ # RUN PARAMETERS ############################################ abort=0 alter=0 auto_throttle=0 backups=1 bitcnt=1 bloom=1 bloom_bit_count=14 bloom_hash_count=4 bloom_oldest=1 cache=62 checkpoints=1 checksum=uncompressed chunk_size=7 compaction=0 compression=zlib data_extend=0 data_source=file delete_pct=49 dictionary=0 direct_io=0 encryption=none evict_max=1 file_type=row-store firstfit=0 huffman_key=0 huffman_value=0 independent_thread_rng=0 in_memory=0 insert_pct=8 internal_key_truncation=1 internal_page_max=10 isolation=read-committed key_gap=19 key_max=94 key_min=28 leaf_page_max=17 leak_memory=0 logging=1 logging_archive=0 logging_compression=none logging_prealloc=1 long_running_txn=0 lsm_worker_threads=3 merge_max=11 mmap=1 modify_pct=15 ops=100000 prefix_compression=0 prefix_compression_min=5 quiet=1 read_pct=0 rebalance=1 repeat_data_pct=13 reverse=0 rows=100000 runs=1 salvage=1 split_pct=83 statistics=0 statistics_server=0 threads=19 timer=360 transaction_timestamps=0 transaction-frequency=24 value_max=1499 value_min=18 verify=1 wiredtiger_config= write_pct=28 ############################################