The system log is commonly stored on a hard disk to ensure data persistence. This storage method allows for recovery after most system failures, except for those directly affecting the disk itself. Cloud storage, RAM, and CPU are not typically used for storing system logs due to various limitations.
The system log is kept on hard disk, so it is not affected by any type of failure except for disk or catastrophic failure.
An explanation for this answer is that the system log needs to be written to a persistent storage device to ensure that the log is maintained across system reboots and shutdowns. The hard disk is such a storage device and is generally used to store logs so that they can be retrieved and analyzed even after a system failure that does not involve the hard disk itself. Although cloud storage and RAM are also used in computing, they are less likely to be used for storing system logs, as cloud storage can be slow and dependent on network connectivity, and RAM is volatile and loses data when power is lost. The CPU is a processor and not a storage device, so it is not relevant for the storage of logs.
In conclusion, system logs are commonly written to the hard disk to allow for data persistence and recovery capabilities in the case of system failures that do not involve the disk itself.