5.9. Red Hat Enterprise Linux-Specific Information

Under Red Hat Enterprise Linux, the device files for disk drives appear in the /dev/ directory. The format for each file name depends on several aspects of the actual hardware and how it has been configured. The important points are as follows:

Because adding or removing mass storage devices can result in changes to the device file names for existing devices, there is a risk of storage not being available when the system reboots. Here is an example of the sequence of events leading to this problem:

In theory, this sounds like a terrible problem. However, in practice it rarely is. It is rarely a problem for a number of reasons. First, hardware reconfigurations of this type happen rarely. Second, it is likely that the system administrator has scheduled downtime to make the necessary changes; downtimes require careful planning to ensure the work being done does not take longer than the alloted time. This planning has the side benefit of bringing to light any issues related to device name changes.

However, some organizations and system configurations are more likely to run into this issue. Organizations that require frequent reconfigurations of storage to meet their needs often use hardware capable of reconfiguration without requiring downtime. Such hotpluggable hardware makes it easy to add or remove storage. But under these circumstances device naming issues can become a problem. Fortunately, Red Hat Enterprise Linux contains features that make device name changes less of a problem.