Rating: 

The title should have been something like "Understanding your system to tune it" because a contrary to many tuning books it does not only gives you some solutions but also (and this is where this book is really above average)makes you understand why your system behaves like it does.

As written on the back cover most of the discussion here concerns Solaris/Sparc although most of the principles can be applied to other unix flavours [One noticeable exception concerns the Solaris Kernel tunables, but perhaps the third editions will cover Solaris, Linux, HP-UX, FreeBSD, NetBSD ;-) ]

If you want an in depth coverage of memory/disk/cpu/network behaviour buy this book, you will not regret it.