ceph/doc/rados/configuration/pool-pg.conf

   1 [global]
   2
   3         # By default, Ceph makes 3 replicas of RADOS objects. If you want to maintain four
   4         # copies of an object the default value--a primary copy and three replica
   5         # copies--reset the default values as shown in 'osd_pool_default_size'.
   6         # If you want to allow Ceph to accept an I/O operation to a degraded PG,
   7         # set 'osd_pool_default_min_size' to a number less than the
   8         # 'osd pool default size' value.
   9
  10         osd_pool_default_size = 3  # Write an object 3 times.
  11         osd_pool_default_min size = 2 # Accept an I/O operation to a PG that has two copies of an object.
  12
  13         # Ensure you have a realistic number of placement groups. We recommend
  14         # approximately 100 per OSD. E.g., total number of OSDs multiplied by 100
  15         # divided by the number of replicas (i.e., osd pool default size). So for
  16         # 10 OSDs and osd pool default size = 4, we'd recommend approximately
  17         # (100 * 10) / 4 = 250.
  18         # always use the nearest power of 2
  19
  20         osd_pool_default_pg_num = 256
  21         osd_pool_default_pgp_num = 256