It usually helps if you ask what you really want to know, instead of something vaguely related to that. We are not adverse to explaining things, but commonly get angry when we get the feeling that we are abused to cover a lack of energy.

Your filesystem is made of volumes, neither raw nor other disks. That is the point of having a logical volume manager.

There is a driver for each certain (type of) disk: SCSI drives, LUNs, whatever. This driver creates a blockdevice and a character device. If you want to use the device directly, you can do that and, for instance, use a program like "dd" to write to it.

Otherwise you give this device to the LVM, which uses it to create Physical Volumes, PVs. "creating PVs" means it writes all sort of management-information onto it, like the VGDA (volume group descriptor area), etc.. Think of this like taking open (raw) land and build roads, create lots, and so on: the land is still unused, but now the means to use it are there.

Now you create Logical Volumes, LVs, on this now usable space. You can use such an LV like a raw device too (and this is sometimes done, for instance with databases), but it is not the same as the raw devices from before, because now this raw space is under control of the LVM and can be handled by its methods: it can be moved to another PV, increased in size, ...

Finally, you can create a filesystem on such an LV, instead of using the provided space directly. You could also create a swap space, a dump device or something entirely different instead. Depending on what you create a certain driver (for filesystems the filesystem driver) will use the LV to create the entity it is designed to provide.

I hope this clears it up a bit.

bakunin