14.7 Summary

Linux on the mainframe can use all supported mainframe devices, such as IBM TotalStorage Enterprise Storage Server (ESS), or the more traditional 3390. Also, support for fiber SCSI over an FCP link will allow Linux images to reach SCSI devices that are common in the UNIX world.

At the end of 2002, it became possible to use SANs in the context of Linux on the mainframe. However, until current security and management issues are resolved, the use of SANs should be restricted to constrained environments.

The mainframe with its channel paths allows an enormous number of directly attached devices. Because your Linux images run in the same physical machine, you can share physical access paths. The large number of configurable paths also provides for multiple channel paths leading to the same device. Multipathing can increase availability and bandwidth.

Although physical connections might be in place, a Linux image cannot access a device unless the mainframe's hardware definition and z/VM definitions permit it. z/VM definitions can be changed dynamically without the need to restart any images or to change any cabling on the machine floor.