[linux-lvm] How to re-stripe a LV after pvmove?

[linux-lvm] How to re-stripe a LV after pvmove?

[Olle Liljenzin]

Hello,

How can I rearrange a striped volume after pvmove has been run, so that 
I get back the original structure with the stripes equally distributed 
on PVs?

/Olle

Re: [linux-lvm] How to re-stripe a LV after pvmove?

[Heinz Mauelshagen]

On Thu, Mar 29, 2007 at 01:42:47PM +0200, Olle Liljenzin wrote:
> Hello,
> 
> How can I rearrange a striped volume after pvmove has been run, so that 
> I get back the original structure with the stripes equally distributed 
> on PVs?

I need to presume, that IO to the striped LV was going on during pvmove.
Hence restoring the old mapping won't help and will lead to data corruption.

pvmove back using the destination options of the command.

> 
> /Olle
> 
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-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Re: [linux-lvm] How to re-stripe a LV after pvmove?

[Olle Liljenzin]

Heinz Mauelshagen wrote:
> On Thu, Mar 29, 2007 at 01:42:47PM +0200, Olle Liljenzin wrote:
>   
>> Hello,
>>
>> How can I rearrange a striped volume after pvmove has been run, so that 
>> I get back the original structure with the stripes equally distributed 
>> on PVs?
>>     
>
> I need to presume, that IO to the striped LV was going on during pvmove.
> Hence restoring the old mapping won't help and will lead to data corruption.
>
> pvmove back using the destination options of the command.
>   

Maybe an example is helpful. After the commands below I have two stripes 
on sdb2 and one on sdb3. How do I move one of the stripes from sdb2 to sdb4?

pvcreate /dev/sdb{1,2,3}
vgcreate vg /dev/sdb{1,2,3}
lvcreate -i 3 -L100M -n lv /dev/vg
vgreduce /dev/vg /dev/sdb1
pvremove /dev/sdb1
pvcreate /dev/sdb4
vgextend /dev/vg /dev/sdb4
lvdisplay -m /dev/vg/lv

--- Logical volume ---
  LV Name                /dev/vg/lv
  VG Name                vg
  LV UUID                NVBrvT-5fZe-0qKA-LCYA-Z9au-X84A-fXYkx3
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                108.00 MB
  Current LE             27
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:2
  --- Segments ---
  Logical extent 0 to 26:
    Type                striped
    Stripes             3
    Stripe size         64 KB
    Stripe 0:
      Physical volume   /dev/sdb2
      Physical extents  9 to 17
    Stripe 1:
      Physical volume   /dev/sdb2
      Physical extents  0 to 8
    Stripe 2:
      Physical volume   /dev/sdb3
      Physical extents  0 to 8

Re: [linux-lvm] How to re-stripe a LV after pvmove?

[Dave Wysochanski]

On Thu, 2007-03-29 at 16:05 +0200, Olle Liljenzin wrote:
> Heinz Mauelshagen wrote:
> > On Thu, Mar 29, 2007 at 01:42:47PM +0200, Olle Liljenzin wrote:
> >   
> >> Hello,
> >>
> >> How can I rearrange a striped volume after pvmove has been run, so that 
> >> I get back the original structure with the stripes equally distributed 
> >> on PVs?
> >>     
> >
> > I need to presume, that IO to the striped LV was going on during pvmove.
> > Hence restoring the old mapping won't help and will lead to data corruption.
> >
> > pvmove back using the destination options of the command.
> >   
> 
> Maybe an example is helpful. After the commands below I have two stripes 
> on sdb2 and one on sdb3. How do I move one of the stripes from sdb2 to sdb4?
> 
> pvcreate /dev/sdb{1,2,3}
> vgcreate vg /dev/sdb{1,2,3}
> lvcreate -i 3 -L100M -n lv /dev/vg
> vgreduce /dev/vg /dev/sdb1
> pvremove /dev/sdb1
> pvcreate /dev/sdb4
> vgextend /dev/vg /dev/sdb4
> lvdisplay -m /dev/vg/lv
> 
> --- Logical volume ---
>   LV Name                /dev/vg/lv
>   VG Name                vg
>   LV UUID                NVBrvT-5fZe-0qKA-LCYA-Z9au-X84A-fXYkx3
>   LV Write Access        read/write
>   LV Status              available
>   # open                 0
>   LV Size                108.00 MB
>   Current LE             27
>   Segments               1
>   Allocation             inherit
>   Read ahead sectors     0
>   Block device           253:2
>   --- Segments ---
>   Logical extent 0 to 26:
>     Type                striped
>     Stripes             3
>     Stripe size         64 KB
>     Stripe 0:
>       Physical volume   /dev/sdb2
>       Physical extents  9 to 17
>     Stripe 1:
>       Physical volume   /dev/sdb2
>       Physical extents  0 to 8
>     Stripe 2:
>       Physical volume   /dev/sdb3
>       Physical extents  0 to 8

looks like you need something like this:

pvmove /dev/sdb2:9-17 /dev/sdb4:0-8

Re: [linux-lvm] How to re-stripe a LV after pvmove?

[Olle Liljenzin]

Yes, it works!

/Olle

Dave Wysochanski wrote:
>
> looks like you need something like this:
>
> pvmove /dev/sdb2:9-17 /dev/sdb4:0-8
>
>