PERC 5/i question

William Warren hescominsoon at
Tue Dec 12 06:59:56 CST 2006

IME with hardware raid you can move the disks between different cards of 
the same RAID level.  I have moved a 3 disk RAID 5 array between 
different controllers more than once without issue.

Ben Scott wrote:
> On 12/11/06, Matt Richardson <marichar at> wrote:
>> Is there an advantage to running software raid vs hardware raid?
>   Software RAID is portable between hardware.  Hardware RAID is
> portable between software.
>   In other words: Using Linux software RAID, you can move disks
> between controllers/machines/etc and still access the same disks.
> Using hardware RAID, you can boot two different OSes (or different
> versions of LVM, etc.) and still access the same disks.
>   Hardware RAID can give you a performance benefit if your machine is
> busy running other tasks.  Software RAID can save you money if your
> CPU/RAM/bus/etc are lightly loaded and can spare the resources.
>   In my experience, hardware RAID tends to be a bit more robust in the
> face of failures, but that might just be coincidence.
>> Is it possible to configure a PERC 5/i (in a PE2950) to not act as a
>> raid controller?
>   You can create a Logical Drive (LD) for each Physical Disk (PD) on
> the controller.  That effectively gives you one-to-one between LDs and
> PDs.  I'm not sure what overhead you'll incurr on the controller,
> though.  It might be you still pay the performance penalty of running
> through the RAID firmware and processor.
>> This is all new to me as I used hardware raid on my
>> previous PEs, no lvm.  However, I like the flexibility lvm offers,
>> especially with xen guests.
>   You can run LVM on top of hardware RAID.  LVM for storage
> management, hardware RAID for reliability.  I've done this before;
> works well.
> -- Ben
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every tongue that shall rise against thee in judgment thou shalt 
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