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Chapter 19. Pre-Installation Preparation and Verification

19.1. Verifying Memory and Swap Space

Oracle states that the system must have at least 512MB of RAM and 1GB of swap space or a swap space twice the size of the RAM. For systems with more than 2 GB of RAM it states the swap space can be between one and two times the size of the RAM. You might also want to read Swap Space.
To check the size of physical memory, execute: 
grep MemTotal /proc/meminfo
To check the size of swap space, execute: 
grep SwapTotal /proc/meminfo