Btier is not a cache but tiered storage that automatically moves frequently accessible data to fast(er) device.

wget http://sourceforge.net/projects/tier/files/STABLE_PRODUCTION/btier-1.3.11.tar.gz
tar -xvf btier-1.3.11.tar.gz -C /usr/src

dkms add -m btier/1.3.11
dkms build -m btier/1.3.11
dkms install -m btier/1.3.11
modprobe btier

#dkms remove -m btier/1.3.11 –all # You can remove if build was not successful

dkms status
btier, 1.3.11, 2.6.XXX, x86_64: installed

btier_setup -f /dev/sdaX:/dev/sdbX -cVz 4096
echo 0 >/sys/block/sdtiera/tier/sequential_landing
fsck -y /dev/sdtiera
mount -o discard,noatime,nodiratime /dev/sdtiera /some_dir/path

Works with Centos OS.

If you have error “Error! Could not locate dkms.conf file”

vi dkms.conf
PACKAGE_VERSION=”1.3.11″
PACKAGE_NAME=”btier”
AUTOINSTALL=”yes”
BUILT_MODULE_NAME[0]=”btier”
BUILT_MODULE_LOCATION[0]=”kernel/btier”
DEST_MODULE_LOCATION[0]=”/kernel/drivers/block”
REMAKE_INITRD=”no”
MAKE[0]=”make -Wall -C ${kernel_source_dir} M=${dkms_tree}/${PACKAGE_NAME}/${PACKAGE_VERSION}/build/kernel/btier modules”