[CentOS] [CentOS-docs] Updating the "RAID1 HowTo" to CentOS 6

On 05/02/12 18:47, Gianni Giardina wrote:
> Hi.
> The following HowTo on the CentOS Wiki:
>
> http://wiki.centos.org/HowTos/Install_On_Partitionable_RAID1
>
> valid for CentOS 5, has not been updated to CentOS 6, yet. I found it
> very useful during the glorious CentOS 5 days and now that I've
> successfully ported my RAID1 experience to CentOS 6, I'd like to share
> it with the Community.

I have a question regarding partionable RAID :
why should the --metadata=0.90 be used?
in my man page (centos 6.2) i have this :
-e, --metadata=
Declare  the  style  of RAID metadata (superblock) to be used.  The 
default is 1.2 for --create, and to guess for other operations.  The 
default can be overridden by setting the metadata value for the CREATE 
keyword in mdadm.conf.

Options are:

0, 0.90	   Use the original 0.90 format superblock.  This format limits 
arrays to 28 component devices and limits component devices of levels 1 
and  greater  to  2  terabytes.   It  is  also possible for there to be 
confusion about whether the superblock applies to a whole device or just 
the last partition, if that partition starts on a 64K boundary.

1, 1.0, 1.1, 1.2 default   Use the new version-1 format superblock. 
This has fewer restrictions.  It can easily be moved between hosts with 
different endian-ness, and a recovery operation can be checkpointed and 
restarted.  The different sub-versions store the superblock at different 
locations on the device, either at the end (for 1.0), at the start (for 
1.1) or 4K from the start (for 1.2).  "1" is equivalent to "1.2". 
"default" is equivalent to "1.2".

given the existence of 2+ tb hdd, metadata 0.9 is no go from the start 
... so, why 0.9 ?

Thanks,
Adrian