Writecache target

modulename: dm-writecache.ko

configname: CONFIG_DM_WRITECACHE

Linux Kernel Configuration
└─>Device Drivers
└─>Multiple devices driver support (RAID and LVM)
└─>Writecache target
In linux kernel since version 4.2 (release Date: 2015-08-30)  
The writecache target caches writes on persistent memory or SSD.
It is intended for databases or other programs that need extremely
low commit latency.

The writecache target doesn't cache reads because reads are supposed
to be cached in standard RAM.

source code: