If you change it to "Write Through" then there is no cache data and cache data corruption/lost can be avoided. It can not guarantee that actual data is not lost during abrupt power lost. You can refer below link for more details on these modes [URL] 
Hi, I've got 2 PowerEdge R720 Servers that are connected to a UPS, however, I've experienced this twice already whereby the UPS batteries were drained and the servers shut down. Upon powering on, both had the error that cached data was lost which shouldn't be a problem but to my surprise, actual data (not cached data) was lost as if it was not written to the disks. I checked the Controller settings and they are both set to "Write Back". Is this the reason for this problem? Battery health is fine, the charge is also full. Do I need to change it to "Write Through"? Will I lose data if I do that?
PowerEdge R720 Corruption After Power Failure