[nycbug-talk] FreeBSD software RAID?

[Andy Michaels]

On Mar 7, 2007, at 10:46 PM, Steven Kreuzer wrote:

>
> On Mar 7, 2007, at 9:48 PM, Miles Nordin wrote:
>
>>>>>>> "jv" == Jonathan Vanasco <nycbug-list at 2xlp.com> writes:
>>
>>     jv> Is there a preferred software raid on FreeBSD ?
>>
>> I think the RAID3 software RAID is theoretically more sound than the
>> RAID5.  I don't have direct experience, but please don't be fooled
>> into the crappier implementation by the larger number.
>
> Cut n Paste from wikipedia because it sums it up better then I can:
>
> RAID 3 uses byte-level striping with a dedicated parity disk. RAID 3
> is very rare in practice. One of the side-effects of RAID 3 is that
> it generally cannot service multiple requests simultaneously.
> This comes about because any single block of data will, by
> definition, be spread across all members of the set and will reside
> in the same location. So, any I/O operation requires activity on
> every disk.
>
> I have never used it at all, but I would stay the hell away from RAID
> 3, both hardware and software implementations
>
> SK
>
So we have Miles saying (I think) that the RAID3 implementation in 
FreeBSD is better than the RAID5 implementation, then Steven saying 
that RAID3 is the redheaded stepchild of disk arrays.  I'm beginning to 
think that software RAID on FreeBSD isn't worth the hassle and a modest 
investment in a supported RAID card is in order.  Is this the real 
recommendation?

-Andy