2.4 LVM1 devfs -> 2.6.0 LVM2 udev

Hi,

As the 2.6.0 is out, it's time for me to see if I can switch to it. What is the procedure and the things to know to switch from a 2.4 LVM1 devfs to a 2.6 LVM2 udev ? I'm using a debian/unstable. I've seen that there was a package lvm2 (2.00.08-3) but the comment contains at the end "requires Linux kernel 2.4.". Does this mean that this package really cannot handle 2.6 kernels ?

I've also seen that devfs has been obsoleted by udev. However, I didn't find a udev package for sid nor a kernel option for it (but I've read that it is only in userspace). The udev FAQ
(http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev-FAQ) does not mention if I need to install hotplug to have udev working.

Do I have to change something in /etc/lvmtab.d and /etc/lvmconf ?

It seems that a thing called "device-mapper" is needed, but I couldn't find it in the kernel. Is it CONFIG_DM_IOCTL_V4 ? The "DM" substring makes me think it's that but the comment in "make menuconfig" doesn't say that it's for LVM nor that it's a device mapper.

Quoted 10 lines · Xavier Brouckaert

Hi,

As the 2.6.0 is out, it's time for me to see if I can switch to it. What is the procedure and the things to know to switch from a 2.4 LVM1 devfs to a 2.6 LVM2 udev ? I'm using a debian/unstable. I've seen that there was a package lvm2 (2.00.08-3) but the comment contains at the end "requires Linux kernel 2.4.". Does this mean that this package really cannot handle 2.6 kernels ?

No, that lvm2/devmapper packages handle 2.6 perfectly well. If you've got an LVM1 setup on your Debian box all you should need to do to switch to LVM2 and 2.6.0 is install the lvm2 packages and reboot into the new kernel.

Quoted 7 lines

I've also seen that devfs has been obsoleted by udev. However, I didn't find a udev package for sid nor a kernel option for it (but I've read that it is only in userspace). The udev FAQ
(http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev-FAQ) does not mention if I need to install hotplug to have udev working.

I don't know about udev or hotplug. They are not required for LVM2/devmapper operation though.

Quoted 3 lines

Do I have to change something in /etc/lvmtab.d and /etc/lvmconf ?

No. lvm-common will detect whether you have device-mapper or LVM1 in the kernel and use the appropriate LVM tools.

Quoted 6 lines

It seems that a thing called "device-mapper" is needed, but I couldn't find it in the kernel. Is it CONFIG_DM_IOCTL_V4 ? The "DM" substring makes me think it's that but the comment in "make menuconfig" doesn't say that it's for LVM nor that it's a device mapper.

Yes, you must compile in IOCTL_V4 support for device-mapper in 2.6.0. (actually I think that may have been fixed now but the old "V1" ioctls are deprecated). CONFIG_BLK_DEV_DM is the device-mapper string but if you don't select that you won't even see the option for IOCTL_V4 !

Hi Patrick,

I have a full ("/" is also a logical volume) LVM1 2.4 devfs system, and I want to test the LVM2 2.6 devfs kernel.

I want to have the possibility to boot the 2.4 or the 2.6 kernel with the same filesystems.

You say "lvm-common will detect whether you have device-mapper or LVM1 in the kernel and use the appropriate LVM tools". What is lvm-common ? And if lvm-common can use the appropriate LVM tools how to install the LVM1 and LVM2 tools in the same filesystem ("same" binaries)

Quoted 9 lines · Francis SOUYRI

Hi Patrick,

I have a full ("/" is also a logical volume) LVM1 2.4 devfs system, and I want to test the LVM2 2.6 devfs kernel.

I want to have the possibility to boot the 2.4 or the 2.6 kernel with the same filesystems.

You say "lvm-common will detect whether you have device-mapper or LVM1 in the kernel and use the appropriate LVM tools". What is lvm-common ? And if lvm-common can use the appropriate LVM tools how to install the LVM1 and LVM2 tools in the same filesystem ("same" binaries)

lvm-common is the Debian package that switches between LVM versions on the same system. If you install the "lvm10" or "lvm2" packages then this will get installed by default.

The Debian LVM binaries get installded lib /lib/lvm-<version> and lvm-common decides at run-tim which one is the most appropriate to use.

Of course you must use the Debian packages to get this, if you build your own tools from source then you're on your own :) (building your own kernels is fine though)

Hi Patrick

Thank yo, I'll try to implement the same installation on my system (no Debian).