By Amit Kumar Saha

What is Software RAID?

Software RAID is RAID implemented with software - no additional hardware such as a RAID controller is needed. Thus, software RAID is a good starting point to start getting some hands-on RAID experience. Also, software RAID is independent of proprietary management software - maintaining a software RAID works the same way on all machines that run Linux. However, there is something to think about too: when considering software RAID, think about performance. All RAID algorithms are done by the system CPU and every block has to be copied over the system's data bus (i.e. sda1 <-> IO controller <-> RAM, possibly CPU <-> IO controller <-> sdb1). (Thanks to René Pfeiffer of the Answer Gang for pointing that out.)

Enabling your Kernel to support RAID

I am using Ubuntu 7.10 with the "stock" kernel for my experiments. The test machine has an 80GB SATA HDD.

First, check whether the RAID support is enabled in your kernel:

cat /proc/mdtstat

If you get a message saying:

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