RAID options under Fedora

Alexandre Oliva aoliva at
Thu Nov 27 01:38:13 UTC 2003

On Nov 26, 2003, "Seth Bardash" <seth at> wrote:

> 1) Software RAID requires the cpu to do 2 reads/writes for each
> read/write the system does.

Wrong.  A single read is enough.  It's write that must get to all
disks.  And this is no different from hardware raid.

> Most of our customers are using CPU cycles for file serving and
> database functions and need all the performance they can get while
> optimizing the RAID functions at a reasonble price.

I'm told a number of the so-called hardware RAID controllers actually
use the CPU for whatever it needs.  Besides, it's not like setting up
writes to a pair of disks is a lot of CPU work if done using DMA.

Software RAID is stable, uses open formats and you can be pretty sure
you can use software to fix things up or even to get to your data,
even if the disk controller fails at the worst possible time and you
can't find a replacement.

Alexandre Oliva   Enjoy Guarana', see
Red Hat GCC Developer                 aoliva@{,}
CS PhD student at IC-Unicamp        oliva@{,}
Free Software Evangelist                Professional serial bug killer

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