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Re: hardware raid vs. software raid



On Thursday, 30.11.2006 at 22:53 +0100, Matus UHLAR - fantomas wrote:

> > > On 30.11.06 15:44, Johannes Wiedersich wrote:
> > > > What is debian's opinion about hardware/software raid?
> 
> > On Thursday, 30.11.2006 at 16:56 +0100, Matus UHLAR - fantomas wrote:
> > > it highly depends on the hardware raid. The true hardware RAID with
> > > hotspare, hotswap etc. support and with proper drivers (so you won't have to
> > > boot into its bios to reconfigure it) will be much more reliable.
> > > 
> > > > On the other hand, performance will probably be better with a dedicated
> > > > hardware raid controller.
> > > 
> > > it highly depends on the hardware raid. The true hardware RAID with XOR
> > > counting and mirroring support will be much faster.
> 
> On 30.11.06 16:01, Dave Ewart wrote:
> > Although it's worth pointing out that software RAID-*1* (one of the
> > options under consideration) has almost no CPU overhead, and is often a
> > good low-cost option.
> 
> I did not want to mention this, because:
> 
> - software RAID-1 has bus overhead (the same data have to be transferred
> multiple times to multiple drives, so writing may be twice as slow)

That's why I also said "Part of your decision must rest on what exactly
the machine will be doing" since one may or may not care about the extra
disk I/O in some environments.  Equally, it could be completely
inappropriate in other environments.

As always, "it depends" :-)

Dave.

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