SATA Raid

Lennart Sorensen lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org
Mon Jun 19 15:22:23 UTC 2006


On Sun, Jun 18, 2006 at 01:52:47PM -0400, CLIFFORD ILKAY wrote:
> A counterpoint: hardware RAID is too dependent on your hardware being 
> supported by the specific version of the kernel module. The MegaRAID 
> fiasco is a good example. I have two servers that have MegaRAID SCSI 
> controllers which were both running pre 2.6.9 kernels. I had added 
> some new drives to the machines and had reconfigured the RAID volumes 
> thus (knowingly) blowing away all the data on the drives. I figured I 
> might as well install a modern distro. Imagine my surprise to find 
> that my previously well-supported RAID controller was no longer 
> automatically detected. I tried various distros thinking that the 
> packagers of first one I tried might have screwed things up but none 
> I tried, other than distros running pre 2.6.9 kernels, detected any 
> volumes. A bit of digging and I found that for some reason, the 
> megaraid modules had been renamed and were no longer included, if 
> memory serves. We're not talking about some exotic or ancient 
> technology that could be deprecated without having much of an impact. 
> We're talking about one of the more popular SCSI RAID controllers on 
> the market. Fortunately, I had no data riding on this.

The megaraid mess is certainly mind bogling.  I have never seen an
explanation for what the heck happened there.  No other hardware raid
has ever gone through that in linux that I know of.

> During the course of searching for answers, I found some convincing 
> arguments as to why hardware RAID was potentially dangerous so I've 
> been happily using software RAID since. Performance? Don't know, 
> don't care. It's "fast enough" but I am reasonably sure now that a 
> kernel upgrade isn't going to render my machine unusable.

Certainly being hardware neutral has its advantages was your raid card
to fail.  Just stick the drives on another card and load the driver and
start the raid again.

> Why is a battery backup for the RAID controller necessary if you have 
> a good UPS and automated shutdown facility?

Idiot touching power switch? :)

Len Sorensen
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