[linux-lvm] Software RAID 5 Resizing and LVM

[Scott Serr]

I have lvm2 on RAID5.  With scratch disks you can do pvmoves to move 
extents off the RAID stripe onto a scratch disk.  Then redo the raid 
stripe wider (more disks).  Then move the extents back.  If you're 
(clever) adding a disk and it's partitioned up a little you can use some 
of the partitions as "scratch" while bringing other partitions into the 
raid.

Does EVMS have something more elegant?  That would be nice.

-Scott

David Greaves wrote:

> For those googling this thread, can I also suggest looking at EVMS.
>
> I'm in the same situation and it appears that EVMS now have an md raid 
> 5 grow facility that manages this up through an 'lvresize' operation 
> and into a xfs_growfs.
>
> I have a 5x250Gb raid5 with lvm2 - I want to grow to 6x250Gb.
>
> Seems neat and doesn't have the 'may eat your babies' threats of 
> raidreconf.
>
> I've not tried it yet so YMMV.
>
> David
> PS I'm LVM2 too
>
>
> Adam K-F wrote:
>
>> Thanks Jon,
>>
>> What I was trying to achieve was a a single, really big raid drive that
>> I could _easily_ expand later on down the track.  It only needs to have
>> the single filesystem on it (i'm going to use reiserfs) which has to be
>> resizable (using resize_reiserfs).
>>
>> So yeah, I ended figuring out what i actally needed to do in the end,
>> after playing with LVM, which incidently was a bit of fun :)  I've found
>> an application for it for my other file server. As they say, all's well
>> that ends well :)
>>
>> Adam
>>  
>>
>>
>> ------------------------------------------------------------------------
>>
>> I asked pretty much that exact question on Monday! :)  The only 
>> difference
>> was that mine is a hardware RAID.  Someone replied with a possible
>> workaround if you're using LVM2, but if you're using LVM1 like me, 
>> and you
>> pvcreate'd your PV across the entire disk like me, then you're 
>> screwed like
>> me. :(
>>
>> If you partitioned the logical disk and pvcreate'd a partition, then you
>> should be able to create a new partition on the newly-available 
>> space, then
>> pvcreate a second PV and add it into the VG.  The wonders of 20/20
>> hindsight.
>>
>> Cheers,
>>
>> Jon Etkins
>> IT Administration & Support
>> Austin Logistics, Inc
>> ph:  (512) 651-5641
>> fax: (512) 329-5625
>>
>>
>> linux-lvm-bounces at redhat.com wrote on 11/16/2004 05:29:54 PM:
>>
>>  
>>
>>> I've been playing around with adding disks to a software RAID 5 array,
>>>   
>>
>> and it
>>  
>>
>>> works fine.  However, i have LVM running over the top of that and i 
>>> can't
>>> figure out how to enlarge the Phisical Volume to encompass the newly
>>>   
>>
>> added
>>  
>>
>>> capacity on the raid device.  Has anyone achieved this at all?
>>>
>>> Am I barking up the wrong tree here? If so, how would you go about
>>> adding drives
>>> to a software RAID 5 device, and actually adding the new space to
>>> the filesystem
>>> inside the RAID device?
>>>
>>> Thanks in advance
>>>
>>> Adam
>>>
>>> ----------------------------------------------------------------
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>>>   
>>
>
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