[SOLVED] pvmove command shifts free space to wrong physical volume

JockVSJock · 01-29-2017, 02:37 PM

I'm trying to move data off of a fdisk partition to a gdisk partition.

/dev/xvdf1 - is the fdisk partition
/dev/xvdg1 - is the gdisk partition

However when trying to move the free space from /dev/xvdf1 to /dev/xvdg1 using pvmove, the free space stays behind, thus I can't extend it out with lvextend command.

I'm not sure where I'm going wrong here:

Code:

[root@linuxacademy dev]# pvcreate /dev/xvdg1
  Physical volume "/dev/xvdg1" successfully created.

[root@linuxacademy dev]# vgextend battlestar /dev/xvdg1
  Volume group "battlestar" successfully extended

[root@linuxacademy dev]# vgdisplay
  --- Volume group ---
  VG Name               battlestar
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               9.99 GiB
  PE Size               4.00 MiB
  Total PE              2558
  Alloc PE / Size       1279 / 5.00 GiB
  Free  PE / Size       1279 / 5.00 GiB
  VG UUID               YzXp39-usMZ-rkeg-AMSM-KECs-upPo-quDY2W

[root@linuxacademy dev]# pvs
  PV         VG         Fmt  Attr PSize PFree
  /dev/xvdf1 battlestar lvm2 a--  5.00g    0
  /dev/xvdg1 battlestar lvm2 a--  5.00g 5.00g

[root@linuxacademy dev]# vgs
  VG         #PV #LV #SN Attr   VSize VFree
  battlestar   2   1   0 wz--n- 9.99g 5.00g

[root@linuxacademy dev]# pvmove /dev/xvdf1
  /dev/xvdf1: Moved: 0.00%
  /dev/xvdf1: Moved: 10.79%
  /dev/xvdf1: Moved: 20.95%
  /dev/xvdf1: Moved: 32.06%
  /dev/xvdf1: Moved: 43.86%
  /dev/xvdf1: Moved: 55.36%
  /dev/xvdf1: Moved: 67.40%
  /dev/xvdf1: Moved: 79.67%
  /dev/xvdf1: Moved: 91.40%
  /dev/xvdf1: Moved: 100.00%

[root@linuxacademy dev]# pvs
  PV         VG         Fmt  Attr PSize PFree
  /dev/xvdf1 battlestar lvm2 a--  5.00g 5.00g
  /dev/xvdg1 battlestar lvm2 a--  5.00g    0

[root@linuxacademy dev]# vgs
  VG         #PV #LV #SN Attr   VSize VFree
  battlestar   2   1   0 wz--n- 9.99g 5.00g

[root@linuxacademy dev]# vgreduce battlestar /dev/xvdf1
  Removed "/dev/xvdf1" from volume group "battlestar"

[root@linuxacademy dev]# pvs
  PV         VG         Fmt  Attr PSize PFree
  /dev/xvdf1            lvm2 ---  5.00g 5.00g
  /dev/xvdg1 battlestar lvm2 a--  5.00g    0

[root@linuxacademy dev]# vgs
  VG         #PV #LV #SN Attr   VSize VFree
  battlestar   1   1   0 wz--n- 5.00g    0

[root@linuxacademy dev]# lvextend -L 5G /dev/battlestar/galacctia
  Logical volume galacctia not found in volume group battlestar.

I don't understand why the free space moves from /dev/xvdg1 to /dev/xvdf1.

I also run vgreduce on /dev/xvdf1 to and no errors.

However when running lvextend against on /dev/xvdg1 there is no free space to extend it out with...

Not sure where I'm going wrong with this.

rknichols · 01-29-2017, 02:56 PM

When you run "pvmove /dev/xvdf1", all of the used extents on that volume get moved elsewhere, and the only "elsewhere" in this case is /dev/xvdg1. So, the 5.00g that had been in use on /dev/xvdf1 are now free (you moved that data away) and the 5.00g that had been free on /dev/xvdg1 is now in use (that's where you moved it to). What did you expect would happen?

Why did you then remove xvdf1 from the volume group? A logical volume can use only space that is within its volume group. Also, in that last command:

Quote:

Originally Posted by JockVSJock

Code:

lvextend -L 5G /dev/battlestar/galacctia

I believe you misspelled "galactica", and thus the LV was not found. Also, "-L 5G" requests that the size be set to 5G, not extended by 5G.

JockVSJock · 01-29-2017, 04:04 PM

Why does the free space stay allocated to the physical volume?

When I run pvmove /dev/xvdf1, and then vgreduce the free space remains tied to the physical volume.

What I'm trying to do is use lvextend in the following way:

Code:

[root@linuxacademy dev]# lvextend -l +100%FREE /dev/battlestar/galactica
New size (5119 extents) matches existing size (5119 extents).

rknichols · 01-29-2017, 04:31 PM

Quote:

Originally Posted by JockVSJock

Why does the free space stay allocated to the physical volume?

When I run pvmove /dev/xvdf1, and then vgreduce the free space remains tied to the physical volume.

That space is in disk sectors that are physically located on that volume.

Quote:

What I'm trying to do is use lvextend in the following way:

Code:

[root@linuxacademy dev]# lvextend -l +100%FREE /dev/battlestar/galactica
New size (5119 extents) matches existing size (5119 extents).

You have removed xvdf1 from the volume group, and now there is no free space in the volume group for extending your LV.

A "volume group" is a group of physical volumes that form a set from which space can be allocated to LVs. An LV can use only space that is within its volume group.

JockVSJock · 01-30-2017, 10:58 PM

This is where I went wrong, for /dev/xvdf1, I was allocating all of the free space and wasn't leaving anything behind. Therefore there was no space to move to /dev/xvdg1

If I only used 1 GB, instead of 20 GB, then there is 19 GB left over and this gets allocated to /dev/xvdg1 when using pvmove and vgreduce command.

thanks