[CentOS] Some 3Ware questions

[Remco Barendse]

On Fri, 9 Sep 2005, Bryan J. Smith wrote:

> Peter Arremann <loony at loonybin.org> wrote:
>> When initializing a raid 1, the controller wipes out all
>> data according to the manuals. Every now and then you hear
>> from people that say that the controller copies everything
>> from disk1 to disk2 and if your IDE controller sector
>> mapping matches what the 3ware controller does, you can
>> keep your data in tact.
>
> Actually, for RAID-1, 3Ware does _not_ using additional
> blocking/organization, and does a direct mirror.  I.e., the
> disks _can_ be used "normally."
>
> For RAID-0, 10 and 5, 3Ware uses 32KiB blocking and the
> volumes are completely _unusable_ by anything else AFAIK
> (maybe LVM2-MD?).

That's not entirely correct. The 3Ware disks almost use standard raid 
format, it's just the raid block on each disk that is written at the end 
of the disk I believe instead of at the beginning. About a year a go we 
rescued all data from a series of PATA disks from a friend of mine when 
his 3Ware went bust. We were able to start the array in software raid with 
the right parameters. Google was my friend then