OT 2nd posting pci ata card ??

[Matthew Kuiken]

Antony Gelberg wrote:
> Matthew Kuiken wrote:
>> I would highly recommend changing to a hardware RAID IDE card.  The 
>> downside to this is that I am not certain that you will not need to 
>> re-install in the process of moving the drives from software RAID on 
>> the MB to the hardware RAID on an add-in card.  It may work, but I 
>> would not hold my breath.
>>
>> The biggest benefit of hardware RAID will be in performance.  You 
>> will get the speed increase of being able to read from mirrored 
>> disks, the reliability of having the two drive system, and the write 
>> speeds won't have the overhead of software needing to perform two 
>> separate writes, the hardware will take care of it.  In all, if you 
>> are adding a card, it is wise to move the RAID functionality into 
>> hardware.
>
> Do you have any evidence to back this up?  Most hardware RAID cards 
> are just normal IDE cards with RAID drivers.  Unless you spend obscene 
> money.  The overhead you speak of is negligible on every system I've 
> used software RAID on.
>
I must apologize.  I was basing my recommendation on my experiences with 
SCSI RAID controllers ~12 years back.  I assumed (bad idea, I know) that 
since the ATA RAIDs are only 0, 1, or 0+1, that they were doing all the 
necessary work in hardware.  It really wouldn't be all that hard to do 
so.  I have done a lot of googling since sending my email, and have 
learned otherwise.  Because of this, I withdraw my recommendation for 
the hardware RAID controller. 

I even found this web site:
http://linux.org.mt/article/ata-raid

which, while old, adequately explains the trade-offs. 
> Software RAID is better for most users as it's not dependent on any 
> specific hardware, and is very configurable.
>
I agree.  Thanks for setting me straight.

I now wonder, what, if anything, do the "ATA RAID" controllers do?  
Other than re-building the disk through the controller BIOS after the 
computer has crashed...

-Matt