How to setup and manage your disk software mirroring

Written by Anze Vidmar on 2005-10-13

Table of contents
1 About
2 Why do you need to mirror your disk?
3 About RAID 1 a.k.a. Mirroring
4 The scenario
5 The first look & feel
6 The GRUB part of setup
7 Disaster planning
8 Disaster recovery / Rebuilding the mirror
9 Conclusion


This is quick HOW-TO setup your mirroring with two exactly the same hard disks. It assumes you’re building a new system from scratch, and setup mirroring at install time. But let’s get something straight first: Software mirroring does not mirror the disks – it mirrors partitions. Thanks to Ed Wilts from Redhat General Newsgroups for this remark. So in this guide I’ll show you how to setup your partitions on one disk and mirror them to another. After that, we will learn how to rebuild our mirrored partitions after one disk dies.

Why do you need to mirror your disk?

Mirroring or RAID 1 if you like, is an easy and not painful (to setup) way of protecting the data, from beeing lost from disk crash. For example, If you keep your private stuff on one partition you can mirror this partition to another on the second drive, and if one disk fails, you will not lose your data, since you have the exact same copy of your files on the second disk. The same goes for the whole filesystem. If you setup mirroring correct, you might never have to reinstall your system again šŸ˜‰



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