Re: Raid-10 mount at startup always has problem

[Bill Davidsen <davidsen@tmr.com>]

Doug Ledford wrote:
> On Fri, 2007-10-26 at 11:15 +0200, Luca Berra wrote:
>   
>> On Thu, Oct 25, 2007 at 02:40:06AM -0400, Doug Ledford wrote:
>>     
>>> The partition table is the single, (mostly) universally recognized
>>> arbiter of what possible data might be on the disk.  Having a partition
>>> table may not make mdadm recognize the md superblock any better, but it
>>> keeps all that other stuff from even trying to access data that it
>>> doesn't have a need to access and prevents random luck from turning your
>>> day bad.
>>>       
>> on a pc maybe, but that is 20 years old design.
>>     
>
> So?  Unix is 35+ year old design, I suppose you want to switch to Vista
> then?
>
>   
>> partition table design is limited because it is still based on C/H/S,
>> which do not exist anymore.
>> Put a partition table on a big storage, say a DMX, and enjoy a 20%
>> performance decrease.
>>     
>
> Because you didn't stripe align the partition, your bad.
>   
Align to /what/ stripe? Hardware (CHS is fiction), software (of the RAID 
you're about to create), or ??? I don't notice my FC6 or FC7 install 
programs using any special partition location to start, I have only run 
(tried to run) FC8-test3 for the live CD, so I can't say what it might 
do. CentOS4 didn't do anything obvious, either, so unless I really 
misunderstand your position at redhat, that would be your bad.  ;-)

If you mean start a partition on a pseudo-CHS boundary, fdisk seems to 
use what it thinks are cylinders for that.

Please clarify what alignment provides a performance benefit.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979