Samskara Monographs
The Samskara Monographs are a series of short papers discussing various aspects of managing enterprise IT environments.
Most of the monographs deal with specific activities relating to managing HP9000-based HP-UX systems; although some deal with more esoteric issues relating to providing effective High Availability solutions irrespective of the underlying Operating System.
The publishing schedule for these documents is to say the least erratic. Most started their lives in mid-to-late 2000 and have been subject to slow evolution since. They will be published here in the order that they reach something approaching a finalised state. Note, however, that the numbering scheme reflects the order in which they were initiated.
Volume I
- Number I - Increasing The Number Of Physical Volumes In A Distrubuted Logical Volume. HP-UX provides a Logical Volume Manager as part of the standard installation. This allows administrators to combine physical disks into volume groups and then allocate slices of this groups (logical volumes) for use by the system; for example to contain a filesystem. There are a number of options available with the product that can be used to improve the overal performance of the environment. One such piece of functionality is ``Distributed Volumes'' which spreads the space allocated to a logical volume across all the disks assigned to the Volume Group. As with all benefits there is a price to be paid; in this case the ability to create distributed volumes requires that a strict allocation policy is set. This means that the space that can be allocated to the disks is less than that which would be available under normal circumstances. In order to effectively manage filesystem growth on enterprise systems it is sometimes necessary to increase the number of physical volumes in a volume group. As described this is not straightforward when logical volumes are distributed across all the existing volumes. This paper describes a methodology for increasing the number of physical volumes allocated in the volume group while still being able to maintain, or even improve, the performance gain available from having distributed volumes.