Configuring your Environment for Software RAID
Understanding Software RAIDUnderstanding Software RAIDRedundant Array of Independent Disks (RAID) is a mechanism that provides storage fault tolerance and, occasionally, better performance. Software RAID is designed on the concept of RAID 1. RAID 1 uses mirroring where data is written to two disks at the same time.
The Serviceguard XDC product uses the Multiple Device (MD) driver and its associated tool mdadm to implement Software RAID. With Software RAID, two disks (or disk sets) are configured so that the same data is written on both disks as one "write transaction". So if data from one disk set is lost, or if one disk set is rendered unavailable, the data is always available from the second disk set. As a result, high availability of data is guaranteed. In an extended distance cluster, the two disk sets are in two physically separated locations, so if one location becomes unavailable, the other location still has the data.
For more information on Linux Software RAID, see The
To enable Software RAID in your extended distance cluster, you need to complete the following:
1.Install the extended distance cluster software.
2.Copy the files into package directories.
3.Configure packages that will use Software RAID.
The subsequent sections include information on installing Extended
Distance Cluster software, and configuring your environment for
Software RAID.
62 | Chapter 3 |