[CentOS] Re: Raid5 issues

Ruslan Sivak rsivak at istandfor.com
Thu May 3 21:03:49 UTC 2007


David A. Woyciesjes wrote:
> Toby Bluhm wrote:
>> Russ wrote:
>>> ...
>>> I would like to set up raid 10 instead, but it doesn't seem like its 
>>> supported by my mdadm - the proper personalities are not loaded.  
>>> How do I get the raid10 personality in there? 
>
>> I don't believe there's a raid10 personality. What you would do is 
>> build your 2 stripe sets, then mirror those striped md's...
>
>     Actually, you have it backwards. Build 2 separate mirror sets, 
> then make a stripe set of those 2 mirrors.
>     Here's why: In your setup, if one drive fails, that whole stripe 
> set is down for the count. You're then running on only 2 drives, no 
> redundancy. The other way, if one drive goes, the other drive in that 
> mirror set keeps going; you're still using 3 drives.
>     Hopefully I explained it clearly... :)
>
>
I have tried this previously, but it's just not possible from anaconda.  
The weird thing is that there is a raid 10 personality... at least 
supposed to be http://cgi.cse.unsw.edu.au/~neilb/01093607424

I think that's the guy that mantains mdadm, and he's talking about 
version 1.7 of mdadm, while I have 2.5.4. 

I can go to shell from anaconda, and build the 2 raid 1 sets and put the 
raid 0 on top of it, but anaconda won't see the raid0.  So there's no 
way to install to it.

I do have a SIL3114 chipset, and I think it's supposed to be supported 
by device mapper.  When I go to rescue mode, I see it loading the driver 
for SIL3112, but nothing appears under /dev/mapper except control.  Are 
there instructions somewhere on getting it to use my controller's raid?

Russ



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