Hot Plug RAID Memory
Hot Plug RAID memory provides a similar level of memory protection as hot-plug mirrored memory but gets this protection from using less total memory. Hot Plug RAID memory protects the server against uncorrectable memory errors that would otherwise result in a server failure.
Although Hot Plug Mirrored memory keeps two copies of all memory data, Hot Plug RAID memory keeps only one copy of all memory data and additional parity information as shown below. If an uncorrectable memory error is encountered, the server can create the proper data using the parity information and the information from the other memory boards that contain no failures. In a Hot Plug RAID memory configuration, 25% of the installed memory is not available to the operating system. In a Hot Plug Mirrored memory configuration, however, 50% of the installed memory is not available to the operating system.
As with hot plug mirrored memory, Hot Plug RAID memory allows failed or degraded DIMMs to be replaced while the server is running without requiring server downtime. The memory board with the failed DIMMs can be removed, failed DIMMs replaced, and the board re-inserted into the server without any interruption to the operating system.