[CentOS] raid1 creation :: not large enough to join array

Les Mikesell lesmikesell at gmail.com
Sat Jan 16 16:46:12 UTC 2010

Adrian Sevcenco wrote:
> Ross Walker wrote:
>> On Jan 16, 2010, at 10:27 AM, Adrian Sevcenco  
>> <Adrian.Sevcenco at cern.ch> wrote:
>>> Hi!
>>> I have 2 identical hdd (1002FBYS) with the same firmware, etc ..  
>>> really
>>> identical! when i try to add the second hdd to this raid1 array i have
>>> the message that /dev/sdb is not large enough to join array!!
>>> on the first hdd i have 100 mb unpartitioned at the end of disk (as i
>>> understood that mdadm put there some info...)
>>> Anyone, any idea what can be wrong? i already done this procees  
>>> several
>>> times and this is first time i encounter this and i have no idea what
>>> can be the problem ..
>> Make sure the partitions are exactly the same, you can use sfdisk to  
>> copy the table from a to b.
> well, i was doing raid over device (md_dX) but i found out the problem :
> even if there are "identical" devices, they have different number of
> blocks (hdparm output). how is this possible?
> is there a way to restrict the number of blocks that a hdd have?
> alternative would be just to clone the first hdd on the "smaller" one
> and then add the big one to and raid1 array ...
> Did someone seen this situation?

I've seen a case where single drive volumes initialized in different (but 
identical) IBM 3550's with adaptec raid controlers would end up with slightly 
different sizes and wouldn't match up if moved.  I think this was a bios or 
firmware difference but I'm not exactly sure.  I was trying to clone disks and 
just started over with the smaller source so it would work everywhere.

   Les Mikesell
    lesmikesell at gmail.com

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