topic Re: lvm filter in Operating System - Linux

lvm filter

ossupport55 — Wed, 30 Sep 2009 07:35:45 GMT

Dear all,

lvm filter in lvm.conf is changed on RHEL 5.3. All the filesystems including the OS are under the control of LVM.
After the change should i be creating the initrd image ?
cheers

Re: lvm filter

Steven E. Protter — Wed, 30 Sep 2009 15:32:08 GMT

Shalom,

If all file systems are lvm your system will not boot.

the /boot filesystem must not be LVM under RHEL 5.x or earlier.

I see no reason to create a new initrd image. If your system doesn't boot it will probably already be trashed and need an OS reinstall or a new kickstart image.

SEP

Re: lvm filter

Matti_Kurkela — Wed, 30 Sep 2009 17:08:28 GMT

If your root filesystem is on LVM, the system must find and activate the root VG (and therefore run vgscan) before it can mount the root filesystem. At that point, the LVM will try to identify any LVM PV it can see.

If your lvm.conf filter is intended to e.g. make the LVM use multipathed disks through the multipath devices and not by accessing the individual /dev/sd* path(s) directly, it is desirable to re-create the initrd image so that the filter will be in effect from the very beginning.

Also, next time you install a kernel update, the system will automatically generate a new initrd for it. If your lvm.conf filter has some unintended side effects when at boot time, they will then manifest themselves... and you will be very confused, as you cannot determine whether the problem was caused by the new kernel or the LVM filter without doing some early-boot troubleshooting.

It's better to recreate the initrd image now rather than leave it for later: as you've made only one configuration change, it will be easy to find and fix the problem if the computer does not boot with the new initrd.

MK

Re: lvm filter

ossupport55 — Wed, 30 Sep 2009 17:37:41 GMT

Thanks folks,

Please put some docs/resources that i could read more abt the lvm.conf changes and the initrd creation.
cheers

Re: lvm filter

Matti_Kurkela — Wed, 30 Sep 2009 19:33:29 GMT

Please run these commands on your system and study their output:

man lvm.conf
man mkinitrd

Bookmark this URL and refer to it as necessary:
https://www.redhat.com/docs/manuals/enterprise/

Also browse and/or search the RedHat Knowledge Base:
http://kbase.redhat.com/

For example, a search for "initrd" found these:
http://kbase.redhat.com/faq/docs/DOC-1959
http://kbase.redhat.com/faq/docs/DOC-1646
http://kbase.redhat.com/faq/docs/DOC-5351

A tip: when you search RHKB and find an article that seems somewhat relevant, use the "Tags:" links at the bottom of the article to find more articles about the same topic.

MK

Re: lvm filter

ossupport55 — Wed, 14 Oct 2009 01:44:17 GMT

Thanks guys