lvm cache

###sdb sdc sdd三块盘，以sdd做缓存，sdb sdc做为数据盘 做 lvm cache

pvcreate /dev/sdb
pvcreate /dev/sdc
pvcreate /dev/sdd

vgcreate datavg /dev/sdb
vgextend datavg /dev/sdc
vgextend datavg /dev/sdd

lvcreate -L 9.9G -n lv_data01 /dev/datavg /dev/sdb
lvcreate -L 9.9G -n lv_data02 /dev/datavg /dev/sdc
lvcreate -L 9.9G -n lv_cache01 /dev/datavg /dev/sdd
lvcreate -L 9.9G -n lv_cache02 /dev/datavg /dev/sdd
lvcreate -L 9.9M -n lv_meta01 /dev/datavg /dev/sdd
lvcreate -L 9.9M -n lv_meta02 /dev/datavg /dev/sdd

lvconvert --type cache-pool --poolmetadata datavg/lv_meta01 datavg/lv_cache01
lvconvert --type cache-pool --poolmetadata datavg/lv_meta02 datavg/lv_cache02

lvconvert --type cache --cachepool datavg/lv_cache01 datavg/lv_data01
lvconvert --type cache --cachepool datavg/lv_cache02 datavg/lv_data02