2012-05-07 // LSI 3ware RAID controller: "Parameter not changeable"

I upgraded the OS of two servers last weekend. The planned downtime was also used to install LSI 3ware 9650SE-4LPML RAID controllers plus Battery Backup Unit (BBU). The BBU enables the controller to keep the write cache during a power failure. However, I was not able to create a RAID array with “Write Cache: enabled” on one system. I always got the message “Parameter not changeable” when the configuration was stored.

The solution was simple: wait. The Battery Backup Unit (BBU) on the system was not charged enough, therefore the controller denied enabling the “Write Cache” setting. So if you get the message “Parameter not changeable” when configuring a LSI 3ware Raid Controller, check if the “Write Cache” setting is the root of it and if a charging or failed BBU caused it. You can check the BBU status in the Controller BIOS Setup (I found “BBU Ready: no” in “Information→Battery”).