Why does the Ceph Rados Gateway full sync process progress slower than expected?

Issue

Issue

• After running the commands radosgw-admin data sync init and radosgw-admin data sync run, the progress of the full sync process is slower than expected.

• Comparing the number of buckets pending full sync, only a few are finished after three days:

  radosgw-admin sync status | grep -e "buckets to sync" -e "current time"
  current time 2023-02-03T11:01:59Z
  full sync: 1106 buckets to sync
  

  Collecting the same command three days later:

  radosgw-admin sync status | grep -e "buckets to sync" -e "current time"
  current time 2023-02-06T09:55:18Z
  full sync: 1078 buckets to sync
  

• Why is this issue occurring? How to speed up this full sync?