There is also an architectural difference in how Linux and Solaris (at least historically) handle swap. Linux adds swap as additional memory, Solaris backs RAM

There is also an architectural difference in how Linux and Solaris (at least historically) handle swap. Linux adds swap as additional memory, Solaris backs RAM with swap. So 32MB RAM plus 64MB swap give you 96MB of allocatable storage on Linux, but 64MB on Solaris. That is the origin of the "twice as much swap as RAM" rule.