You get this alert:
Disk write cache disabled
Disk write cache disabled for disk <disk> on node <node>.
This alert means that the product has detected that write cache is disabled for the drive. As write cache improves performance, it is recommended to have it enabled.
To enable the cache for all the drives of a particular node, please use the next command in the SSH prompt:
sdparm -s WCE /dev/sd? -S
The command enables the write cache for for all /dev/sd drives and sets this option permanently (-S flag). However, if disks are behind a RAID controller, you need to additionally reconfigure the controller to enable write cache. Otherwise write cache will only be available until the next node reboot.
If the command is failing for a device, this means that this device doesn't have the write cache (like SSD).
The alert will be lifted in a few minutes after the command execution.