RHEL6.5 LVM thin volumes and snapshots

gistfile1.txt

[root@backend1 ~]# vgcreate opscode /dev/sdb
  Volume group "opscode" successfully created
[root@backend1 ~]# vgs
  VG       #PV #LV #SN Attr   VSize  VFree
  VolGroup   1   2   0 wz--n- 39.51g    0 
  opscode    1   0   0 wz--n-  2.00g 2.00g
[root@backend1 ~]# lvcreate -L 2G -T opscode/thinpool
  Logical volume "lvol0" created
  Volume group "opscode" has insufficient free space (510 extents): 512 required.
[root@backend1 ~]# lvcreate -L 2000M -T opscode/thinpool
  Logical volume "lvol1" created
  Logical volume "thinpool" created
[root@backend1 ~]# vgs
  VG       #PV #LV #SN Attr   VSize  VFree 
  VolGroup   1   2   0 wz--n- 39.51g     0 
  opscode    1   2   0 wz--n-  2.00g 32.00m
[root@backend1 ~]# lvs
  LV       VG       Attr       LSize   Pool Origin Data%  Move Log Cpy%Sync Convert
  lv_root  VolGroup -wi-ao----  38.60g                                             
  lv_swap  VolGroup -wi-ao---- 928.00m                                             
  lvol0    opscode  -wi-------   4.00m                                             
  thinpool opscode  twi-a-tz--   1.95g               0.00                          
[root@backend1 ~]# lvcreate -T opscode/thinpool -n drbd
  Please specify device size(s).
[root@backend1 ~]# #Need to set a virtual size like -V1G 
[root@backend1 ~]# lvcreate -V1G -T opscode/thinpool -n drbd
  Logical volume "drbd" created
[root@backend1 ~]# # technically the virtual size could be up to 100% of the physical size
[root@backend1 ~]# 
[root@backend1 ~]# lvs
  LV       VG       Attr       LSize   Pool     Origin Data%  Move Log Cpy%Sync Convert
  lv_root  VolGroup -wi-ao----  38.60g                                                 
  lv_swap  VolGroup -wi-ao---- 928.00m                                                 
  drbd     opscode  Vwi-a-tz--   1.00g thinpool          0.00                          
  lvol0    opscode  -wi-------   4.00m                                                 
  thinpool opscode  twi-a-tz--   1.95g                   0.00                          
[root@backend1 ~]# # now to snapshot it
[root@backend1 ~]# lvcreate -s --thinpool opscode/thinpool drbd --name mythinsnap1
  Logical volume "mythinsnap1" created
[root@backend1 ~]# 
[root@backend1 ~]# lvs
  LV          VG       Attr       LSize   Pool     Origin Data%  Move Log Cpy%Sync Convert
  lv_root     VolGroup -wi-ao----  38.60g                                                 
  lv_swap     VolGroup -wi-ao---- 928.00m                                                 
  drbd        opscode  Vwi-a-tz--   1.00g thinpool          0.00                          
  lvol0       opscode  -wi-------   4.00m                                                 
  mythinsnap1 opscode  Vwi---tz-k   1.00g thinpool drbd                                   
  thinpool    opscode  twi-a-tz--   1.95g                   0.00                          
[root@backend1 ~]# mkfs
mkfs          mkfs.cramfs   mkfs.ext2     mkfs.ext3     mkfs.ext4     mkfs.ext4dev  mkfs.msdos    mkfs.vfat
[root@backend1 ~]# # make a filesystem and write some data
[root@backend1 ~]# mkfs.ext4 /dev/opscode/drbd
mke2fs 1.41.12 (17-May-2010)
Discarding device blocks: done                            
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=16 blocks
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376

Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 33 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@backend1 ~]# 
[root@backend1 ~]# mkdir /mnt/drbd
[root@backend1 ~]# mount /dev/opscode/drbd /mnt/drbd
[root@backend1 ~]# cd /mnt/drbd
[root@backend1 drbd]# df -kh .
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/opscode-drbd
                     1008M   34M  924M   4% /mnt/drbd
[root@backend1 drbd]# # write out 500M
[root@backend1 drbd]# dd if=/dev/zero of=500Mfile bs=1M count=512
512+0 records in
512+0 records out
536870912 bytes (537 MB) copied, 1.62417 s, 331 MB/s
[root@backend1 drbd]# 
[root@backend1 drbd]# df -kh .
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/opscode-drbd
                     1008M  546M  412M  58% /mnt/drbd
[root@backend1 drbd]# lvs
  LV          VG       Attr       LSize   Pool     Origin Data%  Move Log Cpy%Sync Convert
  lv_root     VolGroup -wi-ao----  38.60g                                                 
  lv_swap     VolGroup -wi-ao---- 928.00m                                                 
  drbd        opscode  Vwi-aotz--   1.00g thinpool         45.32                          
  lvol0       opscode  -wi-------   4.00m                                                 
  mythinsnap1 opscode  Vwi---tz-k   1.00g thinpool drbd                                   
  thinpool    opscode  twi-a-tz--   1.95g                  23.20                          
[root@backend1 drbd]# 
[root@backend1 drbd]# lvcreate -s --thinpool opscode/thinpool drbd --name mythinsnap2
  Logical volume "mythinsnap2" created
[root@backend1 drbd]# lvs
  LV          VG       Attr       LSize   Pool     Origin Data%  Move Log Cpy%Sync Convert
  lv_root     VolGroup -wi-ao----  38.60g                                                 
  lv_swap     VolGroup -wi-ao---- 928.00m                                                 
  drbd        opscode  Vwi-aotz--   1.00g thinpool         54.77                          
  lvol0       opscode  -wi-------   4.00m                                                 
  mythinsnap1 opscode  Vwi---tz-k   1.00g thinpool drbd                                   
  mythinsnap2 opscode  Vwi---tz-k   1.00g thinpool drbd                                   
  thinpool    opscode  twi-a-tz--   1.95g                  28.04                          
[root@backend1 drbd]# 
[root@backend1 drbd]# dd if=/dev/zero of=256Mfile bs=1M count=256
256+0 records in
256+0 records out
268435456 bytes (268 MB) copied, 0.261732 s, 1.0 GB/s
[root@backend1 drbd]# 
[root@backend1 drbd]# lvs
  LV          VG       Attr       LSize   Pool     Origin Data%  Move Log Cpy%Sync Convert
  lv_root     VolGroup -wi-ao----  38.60g                                                 
  lv_swap     VolGroup -wi-ao---- 928.00m                                                 
  drbd        opscode  Vwi-aotz--   1.00g thinpool         79.77                          
  lvol0       opscode  -wi-------   4.00m                                                 
  mythinsnap1 opscode  Vwi---tz-k   1.00g thinpool drbd                                   
  mythinsnap2 opscode  Vwi---tz-k   1.00g thinpool drbd                                   
  thinpool    opscode  twi-a-tz--   1.95g                  40.85