I have got a strange error while working through the project....

I am using dmsetup to make flash drive as cache to hard disk by the
below command

/dev/sdb1 --> flash drive
/dev/sda1 ---> hard disk

>>echo start_offset_disk end_offset_disk cache /dev/dsa1 /dev/sdb1 | dmsetup create foo

I am getting following error:
device-mapper: reload ioctl failed: Invalid argument
Command failed

any body have any idea about this...plz reply....

and i am also not sure about the start_offset_disk and
end_offset_disk....presently i am using the values output by fdisk -l
below

>fdisk -l

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x68000000

Device Boot Start End Blocks Id System
/dev/sda1 * 1 3200 25702400 7 HPFS/NTFS
/dev/sda2 3201 9701 52219282+ 7 HPFS/NTFS
/dev/sda3 9702 16204 52224000 7 HPFS/NTFS
/dev/sda4 16205 19457 26129722+ 5 Extended
/dev/sda5 16205 16452 1992028+ 82 Linux swap / Solaris
/dev/sda6 16453 19457 24137631 83 Linux

Disk /dev/sdb: 4005 MB, 4005527552 bytes
255 heads, 63 sectors/track, 486 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x0005ce7e

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 487 3911552 b W95 FAT32
Partition 1 has different physical/logical endings:
phys=(485, 254, 63) logical=(486, 248, 1


so for example my command goes like this:

>>echo 1 3200 cache /dev/sda1 /dev/sdb1 | dmsetup create foo

device-mapper: reload ioctl failed: Invalid argument
Command failed

plz reply Its urgent