[rhn-users] need advice on managing partition size (LVM / RAID hardware)

[Frederic Medery]

Yes,
it seems perfect but to create a new raid 5 disk array  I will need 3 
new disks instead of adding 1 to the first raid array.


Frederic Medery
System Administrator

LexUM, University of Montreal


Jesse Becker wrote:

>On Mon, Sep 27, 2004 at 10:15:03AM -0400, Frederic Medery wrote:
>  
>
>>I have a 1 TB RAID 5 hardware. I would like to use LVM to manage 
>>partition size but  :
>>When I'll add extra storage (inside the raid 5), Linux will see extra 
>>free space but i won't be able to resize ma LVM partition ( i think). So 
>>now, I'm thinking of NOT using LVM and create all my partition with the 
>>RAID. So, when  I add extra storage, I just have to add this disk to the 
>>partition that need it and then resize the File system size.
>>    
>>
>
>I was all set to write an email about how you can't add drives to an existing
>RAID array, then found that it might be possible.  However, generally,
>if you wish to add more space, you either must do one of two things:
>
>	1) leave the existing 1TB array alone and create a new storage
>	"thing" (ranging from a lone disk with no RAID, to a new RAID
>	array of some level),
>
>	2) destroy the existing RAID5 array, add the new drives, then create a new
>	(and larger) array using the additional disks.
>
>It seems that there is a tool called 'raidrecof' that might do the trick.
>Make backups of your data, and have a look at it.
>
>  
>
>>Is it a good solution ? I would prefer LVM because resizing would be 
>>only but cannot see how to able it with Hardware RAID 5.
>>    
>>
>
>I would suggest using LVM anyway, and not resize the arrays.  You already
>have one RAID array.  Use this as a physical volume (/dev/sda1, or
>whatever is appropriate) in a volume group (/dev/vg0, for example),
>and create your logical volumes within that.  When it comes time to
>add more space, create a second RAID array (/dev/sdb), and add it to
>the existing volume group that you already have.  That group can then
>make use of the new space, either to create additional logical volumes,
>or increase the size of existing ones.
>
>If this is hardware RAID (as opposed to software /dev/md devices), the
>controller should support multiple arrays.
>
>  
>
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