[root@xxxxxxxxx root]# lvcreate -c 4k --size 2048m --snapshot --name snap1 /dev/mysql/data...
lvcreate -- WARNING: the snapshot will be automatically disabled once it gets full
lvcreate -- ERROR "Cannot allocate memory" creating VGDA for "/dev/mysql/snap1" in kernel
So how is 4 gigs not enough ram?
Ask on the LVM list, since you didn't get an answer here:
http://www.sistina.com/products_lvm_mailing%20list.htm
