You can share your minidisks, but it is impossible to disable caching in the way you want. Caching buffers is a core design decision of UNIX/Linux. However, you do not need to disable it. The usual trick is to mount all shared filesystems read-only.
See one of the classical white papers on the topic - from Oct 2000 - at http://www.ibm.com/servers/eserver/zseries/library/whitepapers/pdf/trilogy_technical_notes.pdf Cloning of a master image set makes also a heavy use of the idea of dasd sharing, iyou can read a lot of about it in the following redbooks: Linux on IBM zSeries and S/390: ISP/ASP Solutions Linux on IBM zSeries and S/390: Performance Measurement and Tuning Sándor Bárány -- "Growing Old is Mandatory, Growing Up is Strictly Optional"
