Ceph » RADOS

tier ops that add refs into the low_tier pools can hit overlap offset which causing few empty entries in low_tier objects

recreate:
1. run command:
ceph_test_rados --set_chunk --enable_dedup --low_tier_pool low_tier --dedup_chunk_size 131072 --dedup_chunk_algo fastcdc --max-ops 1500 --objects 50 --max-in-flight 16 --size 4000000 --min-stride-size 400000 --max-stride-size 800000 --max-seconds 0 --op read 100 --op write 25 --op delete 10 --op set_chunk 30 --op tier_promote 10 --op tier_evict 10 --op tier_flush 5 --op write_excl 25 --pool unique_pool_0

2. list the object in low_tier pool: rados -p low_tier ls

3. dump the chunk reference of one of the chunks:
ceph-dedup-tool --op dump-chunk-refs --chunk-pool low_tier --object 39dc6354c287437fcfba3f3e2c5f4c3837e563dbb69566160498140cbd2219ae

it should return json, few of them are empty.
if we check the osds log for those refs. we will see overlap error.