[CentOS] Re: raid5 crash

[Chris Mauritz]

Aleksandar Milivojevic wrote:

> Farkas Levente wrote:
>
>> what happends if the 3ware card get wrong? do you always have a 
>> backup raid controller (with the same type)? with software raid you 
>> can plug it to any kind of controller and save your data!
>
>
> Can't answer for Bryan, but:
>
> How often you get raid controller card go wrong (or any other PCI card 
> for that matter)?  Sure, if you are careless when handling it and 
> static electricity that accumulated in your body fries it.  Those 
> installed in production servers, very darn close to never.
>
> Even with that, if you keep a number of servers running, you usually 
> standardize on the cards you use (for example, you go with 3ware and 
> stick with them, or you go with Adaptec and stick with them).  Having 
> a spare card or two in a drawer is a good idea anyhow, if you 
> unexpectedly need to build the server overnight.  And usually, you 
> don't need to have exact same model of the card.  In most cases, cards 
> produced by one manufacturer can read RAID metadata information 
> written by different card models (of the same manufacturer).  So you 
> can access your data as long as the replacement card has enough ports 
> to connect all disks from failed card.


I can verify that if a 3Ware card fails, you can simply plug in another 
3Ware card and it reads some magic bits from the array on startup and 
just plain works.  I've done this with both 7X00 and 8X00 cards.  
However, a failed card is extremely rare.  I think I've had exactly 2 
fail (in a universe of 50-75 total cards) over the course of 5 or 6 
years.  It is FAR more likely that you'll lose a disk than the hardware 
RAID card.  I can't imagine why the original poster is using the 3Ware 
card as a "dumb" IDE controller.  That makes *zero* sense.  It's at 
least as reliable (and maybe moreso) than the Linux software RAID bits 
(which is also pretty darned reliable).

Cheers,

C