A controller may report errors or fail on a U144/U840 storage array. A controller may need to be replaced. The process is simple and only takes a few minutes.
Dell sells the storage as a Powervault ME4 storage array and has provided extensive manuals and videos for servicing the unit.
The error in the store.zip file logs will look like:
B1145 2023-10-22 07:56:53 314 ERROR There is a problem with a FRU. (FRU type: Controller B CompactFlash, enclosure: 0, product ID: N/A, SN: <serial_here> , version: FW1138, related event serial number: B1144, related event code: 242)
B1146 2023-10-22 07:56:53 202 INFORMATIONAL Auto-write-through: Write-back cache was reenabled.
From /var/log/messages it will look like:
2023-10-22T09:00:18-04:00 hostname POWERVAULT[144896]: snlog: sn="XX:XX:XX:XX:XX" id="DS" m="23" c="6" event="DISK_STATUS" category="HARDWARE" ip="192.168.0.2" model="R640xl" msg="Auto-write-through trigger event: CompactFlash failed.; "
2023-10-22T09:00:18-04:00 gaxgpnm212 POWERVAULT[144900]: snlog: sn="XX:XX:XX:XX:XX" id="DS" m="23" c="6" event="DISK_STATUS" category="HARDWARE" ip="192.168.0.2" model="R640xl" msg="The periodic monitor of CompactFlash hardware detected an error. The controller was put in write-through mode, which reduces I/O performance. (p1: 1); "
Other errors may indicate a controller failure and will be added to this document, when found.
The controller can be replaced while the system is serving data. Dell has produced a video which best explains the steps to replace the controller. The video titled "DellEMC Storage ME4084/ME484: Remove/Install Control Module" is found on youtube at https://www.youtube.com/watch?v=6NbHiaR6Lh4