corrected some confusing numbers

Signed-off-by: Robert Jansen <r.jansen@fairbanks.nl>

diff --git a/doc/rados/operations/placement-groups.rst b/doc/rados/operations/placement-groups.rst
index 9ed72f32d53e9a596c89d5c0e03a33ec52fa4cc7..3d72ecc9b5426bb08ba5a8dcfb3e6748c9e0d431 100644 (file)
--- a/doc/rados/operations/placement-groups.rst
+++ b/doc/rados/operations/placement-groups.rst
@@ -178,17 +178,17 @@ increased.
 
 No matter how short the recovery time is, there is a chance for a
 second OSD to fail while it is in progress. In the 10 OSDs cluster
-described above, if any of them fail, then ~8 placement groups
-(i.e. ~75 / 9 placement groups being recovered) will only have one
+described above, if any of them fail, then ~17 placement groups
+(i.e. ~150 / 9 placement groups being recovered) will only have one
 surviving copy. And if any of the 8 remaining OSD fail, the last
-objects of one placement group are likely to be lost (i.e. ~8 / 8
+objects of two placement groups are likely to be lost (i.e. ~17 / 8
 placement groups with only one remaining copy being recovered).
 
 When the size of the cluster grows to 20 OSDs, the number of Placement
 Groups damaged by the loss of three OSDs drops. The second OSD lost
-will degrade ~2 (i.e. ~35 / 19 placement groups being recovered)
-instead of ~8 and the third OSD lost will only lose data if it is one
-of the two OSDs containing the surviving copy. In other words, if the
+will degrade ~4 (i.e. ~75 / 19 placement groups being recovered)
+instead of ~17 and the third OSD lost will only lose data if it is one
+of the four OSDs containing the surviving copy. In other words, if the
 probability of losing one OSD is 0.0001% during the recovery time
 frame, it goes from 8 * 0.0001% in the cluster with 10 OSDs to 2 *
 0.0001% in the cluster with 20 OSDs.