[CentOS] Problem with dual-booting soft-RAID

Fri Jun 9 16:31:17 UTC 2006
Kai Schaetzl <maillists at conactive.com>

Scott Silva wrote on Thu, 08 Jun 2006 09:29:12 -0700:

> Pardon my chiming in,

why should I take offense? Thanks!

 but this is an adequate way to copy the partition data, 
> and that is what I used on my software raid systems. Don't forget that the 
> first part is sfdisk -d, not just sfdisk -.

Yeah, my typing! Thanks for the confirmation, I'll put it in my basket of 
valuable snippets.

> > the pulled out one. I didn't test dropping one of the disks in the middle 
> > of operation yet. 
> Don't do that! Don't test by pulling a running disk unless it is in hotplug 
> capable hardware. Test by using mdadm to remove that drive. 

That's not a real test ;-) I can test out and learn quite a few things by less 
harmful ways but I don't know what happens if I rip it out in the middle of 
operation. After all, that's what's going to happen when it really fails. I did 
it already once and the drive survived, I'll do it again. I use two old 10 GB 
drives for testing. I'd regret if I lost one of them since after that I have 
only *very* old drives for further testing, but it's not a real problem.

>  
> > There are two things I realized: 
> > 
> > 1. disks need to run on different IDE controllers it seems. 
> That info is in the software raid howto. Some systems are more tolerant than 
> others, but usually a failed drive will lock the entire channel, so the 
> primary and the slave would go down.

Yeah, I didn't read that part of the how-to I guess. On a non-testing machine I 
wouldn't have put the drives on one channel, anyway, but in this case it was the 
easiest and fastest option. And I learned something from that :-) Actually, they 
didn't go down both, but the bootup failed. There was a whole lot of IDE errors 
on the console, though, after I pulled the cable.

Kai

-- 
Kai Schätzl, Berlin, Germany
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