no file system after replacing bad RAID drive

[Alex Zbyslaw]

Palle Girgensohn wrote:

>
> Well, before replacing the disk, the file system worked OK (only 
> degraded, no redundancy). The Dell guy replaced the disk while the 
> system was shut off, Dell thinks that may have something to do with, 
> but it sounds strange to me. When disk was inserted, it seemed like it 
> was rebuilding, since all disks in the cluster where flashing vividely.
>
I don't know how to solve your problem but I bet the answer lies with 
the RAID BIOS, assuming you have any data left...

What we found when testing this controller with RAID-1 is that you 
*never* replace a disk while the machine is off as the controller then 
has no knowledge about what has happened.  If you had pulled the bad 
disk and pushed the new one with everything switched on I would bet that 
it would have worked fine.  We rebuilt a RAID-1 with FreeBSD running 
just to be sure that we could.

Are you sure that the rebuild didn't for example, copy the blank disk to 
the good disks?  (Certainly something we managed to do with RAID-1 (in 
testing!), but might not happen so easily for RAID-5).

 From what I recall, there should have been no reason to mess around 
with megarc other than to monitor the rebuild.

--Alex