Re: Re: [linux-lvm] Software RAID 5 Resizing and LVM

Re: Re: [linux-lvm] Software RAID 5 Resizing and LVM

[Adam K-F]

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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

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From: Jetkins@austinlogistics.com
To: adam@slackguy.net
Subject: Re: [linux-lvm] Software RAID 5 Resizing and LVM
Date: Wed, 17 Nov 2004 10:53:00 -0600
Message-ID: <OF26153F74.622A298A-ON86256F4F.005C138B-86256F4F.005CBE3E@austinlogistics.com>


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@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
>
> ----------------------------------------------------------------
> This message was sent using IMP, the Internet Messaging Program.
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] Software RAID 5 Resizing and LVM

[David Greaves]

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@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
>>
>>----------------------------------------------------------------
>>This message was sent using IMP, the Internet Messaging Program.
>>
>>_______________________________________________
>>linux-lvm mailing list
>>linux-lvm@redhat.com
>>https://www.redhat.com/mailman/listinfo/linux-lvm
>>read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>    
>>

Re: [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@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
>>>
>>> ----------------------------------------------------------------
>>> This message was sent using IMP, the Internet Messaging Program.
>>>
>>> _______________________________________________
>>> linux-lvm mailing list
>>> linux-lvm@redhat.com
>>> https://www.redhat.com/mailman/listinfo/linux-lvm
>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>>   
>>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] Software RAID 5 Resizing and LVM

[David Greaves]

Oh yes :)

It now has an 'add new disk to raid5 array and rebuild parity whilst 
keeping your data' feature :)
It has to be done 'offline'.

I'm actually just installing it at the moment.

see:
http://evms.sourceforge.net/user_guide/#resizemdreg

also:
http://marc.theaimsgroup.com/?l=evms-devel&w=2&r=1&s=raid5&q=b

David

Scott Serr wrote:

> 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
>

Re: Re: [linux-lvm] Software RAID 5 Resizing and LVM

[Garrick Staples]

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> Date: Wed, 17 Nov 2004 10:53:00 -0600
> From: Jetkins@austinlogistics.com
> Subject: Re: [linux-lvm] Software RAID 5 Resizing and LVM
> To: adam@slackguy.net
> 
> 
> 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.

I'm using the entire, unpartitioned, block device on my boxes on advice from my
DataDirect Networks vendor.  Apparently putting a partition table at the front
of the block device offsets each write request 512 bytes, which is disasterous
for performance.  By using the whole device, the writes are correctly byte
aligned to the arrays.

-- 
Garrick Staples, Linux/HPCC Administrator
University of Southern California

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