Ben's notes

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~~TOC~~

LVM - Thin provisioning

# create thin pool
lvcreate -L 200G vg_kvm1/thinpool

# create thin lv
lvcreate -V32G -T vg_kvm1/thinpool -n thin_vmpxe

# create thin pool and lv in one command
lvcreate -L 200G -T vg_kvm1/thinpool -V32G -n thin_vmpxe

Convert thick LV to thin LV in use by KVM guest

Shutdown access to lv, for example shut down KVM guest using that thick LV.
```
virsh shutdown vmpxe
```

Create thin lv.

lvcreate -V16G -T vg_kvm1/thinpool -n thin_vmpxe

Copy contents from thick to thin lv.

dd if=/dev/vg_kvm1/vmpxe of=/dev/vg_kvm1/thin_vmpxe

##or use 'pv' to monitor progress.

dd if=/dev/vg_kvm1/vmpxe | pv -s 32g | dd of=/dev/vg_kvm1/thin_vmpxe

## free space not yet available:
lvs
  LV         VG      Attr       LSize   Pool     Origin Data%  Move Log Cpy%Sync Convert
  thin_vmpxe vg_kvm1 Vwi-aotz--  32.00g thinpool        100.00

Edit KVM guest disk location.
```
virsh edit vmpxe
```
Start KVM guest.
```
virsh start vmpxe --console
```
Enable issue discards in lvm.conf, 'discard' in /etc/fstab, regenerate initramfs (dracut -f)

create file xml:

<controller type='scsi' model='virtio-scsi' index='0'/>
# virsh attach-device --config Guest1 ~/virtio-scsi-controller.xml

make sure discard=unmap, bus = scsi and address type is altered to scsi instead of pci:

<disk type='file' device='disk'> 
  <driver name='qemu' type='raw' discard='unmap'/>
  <source file='/guests/Fedora19.img'/>
  <target dev='sda' bus='scsi'/>
  <address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>