hdparm fails if called to often to fast:

The operation has completed successfully.
+ hdparm -z /dev/sdb

/dev/sdb:
 re-reading partition table
+ /sbin/sgdisk --largest-new=0 --mbrtogpt -- /dev/sdb
Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot or after you
run partprobe(8) or kpartx(8)
The operation has completed successfully.
+ hdparm -z /dev/sdb

/dev/sdb:
 re-reading partition table
 BLKRRPART failed: Device or resource busy

ceph-osd-create-start

@@ -43,19 +43,21 @@ dev_block="/dev/disk/by-partuuid/$uuid_block"
              --typecode=0:4fbd7e29-9d25-41b8-afd0-062c0ceff05d \
              --mbrtogpt -- $DEV
 
-hdparm -z "$DEV"
+sleep 2 ; hdparm -z "$DEV"
 
 # Using gdisk --largest-new does not change the name or set guid;
 # So use 2 steps instead
 /sbin/sgdisk --largest-new=0 --mbrtogpt -- $DEV
-hdparm -z "$DEV"
+
+sleep 2 ; hdparm -z "$DEV"
 
 lastpart=$(gdisk -l $DEV | tail -n1 | awk '{ print $1 }')
 /sbin/sgdisk --change-name="${lastpart}:ceph block" \
              --partition-guid="${lastpart}:$uuid_block" \
              --typecode="${lastpart}:cafecafe-9b03-4f30-b4c6-b4b80ceff106" \
              --mbrtogpt -- $DEV
-hdparm -z "$DEV"
+sleep 2 ; hdparm -z "$DEV"
+
 
 
 /sbin/mkfs -t xfs -f -i size=2048 -- "$dev_metadata"