XTrim is a service added by Nutanix AOS 5.10.2 onwards. Nutanix AOS runs on the controller VM and manages the disks.
Xtrim is used to improve the write performance. XTrim uses TRIM command supported by the SSD. Whenever there is a
write on a previously written block, the content will not be erased immediately. On the next write the content is erased.
This causes write performance to degrade as there is an erase operation. TRIM command assist the Operating System to
let the SSD know to wipe the pages of blocks immedeately when a delete command issues by the user or OS.Below is a short article on the XTrim service and how it works with Nutanix.
Source: Nutanix services: Xtrim – what it is and why it is needed | Nutanix Community