Chapter FIVE. Disks and Volumes : RAID Levels and RAID Parity Data Chapter Syllabus 5.1 RAID Levels 5.2 RAID Parity Data Managing disk space is a perpetual problem for any administrator. As a CSA, you should have a good idea of the major tasks involved in creating and managing volumes, everything from a simple whole disk partition to LVM and even an understanding of VxVM. Currently, these are the three major disk management techniques we have on HP-UX. Whole disk partitions are not commonly used these days. As a CSA, you should know and understand when and how to use whole disk partitions. We do not discuss them in this book. You should also be familiar with techniques in establishing which of your disks are currently in use, e.g., bdf , swapinfo , crashconf , /etc/fstab , and so on, and with the help of an ioscan output establish which disks are currently not in use by any Operating System utilities. Before discussing the advanced options for LVM And VxVM in detail in the next two chapters, we should first discuss RAID, the background behind the technology, as well as the major RAID levels currently in use: -
Review of RAID levels : Both LVM and VxVM offer software RAID capabilities. It is worth ensuring that we understand the common RAID levels and the underlying technologies they use. -
RAID parity data : We have all probably heard of the term parity data . How many of us actually know the most common ways to calculate parity data? If a disk drive fails, the parity data is used to somehow, magically resurrect our real data . How does it do it? The secret is in mathematical truth tables. |
