On task T271417 we found that it would help decrease significantly the write latency if we disable the write cache on the disks (original source https://yourcmc.ru/wiki/Ceph_performance).
This task is to puppetize the disabling of the caches on all osd devices.
How to manually check:
hdparm -W <path_to_device> ex: hdparm -W /dev/sdc /dev/sdc: write-caching = 0 (off)
How to disable:
hdparm -W 0 <path_to_device> ex: dcaro@cloudcephosd1001:~$ sudo hdparm -W 0 /dev/sdc /dev/sdc: setting drive write-caching to 0 (off) write-caching = 0 (off)