[Gllug] A SATA Raid card worth having?

[Ian Northeast]

Martin A. Brooks wrote:
> Tethys wrote:

(about the contents of a hardware RAID getting munched by replacing the 
RAID controller with one with later firmware)

>> I wish I could say this was a rare occurrence, but
>> sadly it doesn't seem to be.

> I have never experienced this, nor has anyone in my immediate circle of 
> technical colleagues, nor anyone in their circles either.

I have seen it, with the Symbios controller in an IBM 335 series server. 
These are 1U units with space for only 2 disks so you can only do RAID1. 
The RAID adapter failed so IBM replaced the MB, as it is on board in 
these, and it came back with 2 separate disks. Each disk was OK and 
contained exactly what the array had, but there was no way to join the 
array back again. At least, neither IBM's engineer nor I could find one.

So no data was lost, but we had to boot off one of the disks, back up 
the data, recreate the RAID, reinstall Linux and restore the data. After 
this process the array was about 10MB smaller than the previous incarnation.

This doesn't happen with the ServeRAID controllers in the higher 
specification IBM servers, which are the only hardware RAID controllers 
I've used which I've liked (but we use exclusively IBM kit so there are 
a number I have not used). There's still a potential gotcha with these, 
as the driver has to be at at least the same level as the firmware. So 
if the controller has to be replaced and the driver is old, you may have 
to boot off a CD and update the driver before it'll boot off disk. But 
I've not experienced this so it's only theory. It might work well enough 
to last until you can update the driver.

Regards, Ian





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