LVM-Howto [Was : what are the restrictions on bootablepartitions?]
neil
neilcuk at aol.com
Fri Apr 30 09:26:25 UTC 2004
ow.mun.heng at wdc.com wrote:
>
>
>>-----Original Message-----
>>From: neil [mailto:neilcuk at aol.com]
>>
>>
>>mr700 at globalnet.bg wrote:
>>
>>
>>
>>>On Friday 30 April 2004 05:11, Ow Mun Heng wrote:
>>>
>>>
>>>
>>>
>>>>>-----Original Message-----
>>>>>From: neil [mailto:neilcuk at aol.com]
>>>>>Sent: Thursday, April 29, 2004 10:35 PM
>>>>>To: For users of Fedora Core releases
>>>>>Subject: Re: what are the restrictions on bootable partitions?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>rpjday at mindspring.com wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>what are the restrictions on where i can install another
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>linux distro
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>onto my fedora core (actually, FC2-t3) system so that grub
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>can find it?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>(even though this is a test version of fedora, this
>>>>>>
>>>>>>
>>question actually
>>
>>
>>>>>>refers to FC distros in general.)
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>There are no restrictions other than the boot loader (grub)
>>>>>must be able
>>>>>to read the boot partition.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>typically, for historical reasons, even when i use LVM, i
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>create a small
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>primary, ext3 filesystem for /boot, and use LVM for the rest
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>of the drive.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>is there any compelling reason for doing this anymore?
>>>>>>
>>>>>>
>>what's the
>>
>>
>>>>>>recommended strategy for LVM? and need for a non-LVM
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>filesystem on newer
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>machines?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>It really depends on what the system will be used for.
>>>>>
>>>>>
>>Check out the
>>
>>
>>>>>howto here: http://www.tldp.org/HOWTO/LVM-HOWTO/index.html
>>>>>
>>>>>
>>>>>
>>>>>
>>>>I've actually looked through the howto but am still unable
>>>>
>>>>
>>to determine
>>
>>
>>>>how to actually create a lvm system. I've recompiled my kernel to
>>>>have the devive mapper as a module and modprobe'ed it.
>>>>
>>>>When I try to do vgscan it states that the kernel modules
>>>>
>>>>
>>are not loaded.
>>
>>
>>>>
>>>>
>>>>
>>>>
>>> I don't remember how I did this with RH9 to make it
>>>
>>>
>>work, but I remember
>>
>>
>>>I played a bit whth modprobe, the LVM tools and the man pages :)
>>>
>>>
>>>
>>>
>>>>Please help.
>>>>
>>>>
>>>>
>>>>
>>>http://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/s
>>>
>>>
>>ysadmin-guide/ch-lvm.html
>>
>>
>>>http://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/s
>>>
>>>
>>ysadmin-guide/ch-lvm-intro.html
>>
>>
>>>http://www.redhat.com/docs/manuals/linux/RHL-8.0-Manual/custo
>>>
>>>
>>m-guide/ch-lvm.html
>>
>>
>>>http://www.redhat.com/docs/manuals/linux/RHL-8.0-Manual/custo
>>>
>>>
>>m-guide/ch-lvm-intro.html
>>
>>
>>>http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/custom-
>>>
>>>
>>guide/ch-lvm-intro.html
>>
>>
>>>...
>>> I did install FC1 with Software Raid 5 and LVM on top of
>>>
>>>
>>it, but doing so on less
>>
>>
>>>than three physical disks results to up to 5 times slower
>>>
>>>
>>transfer (because of the
>>
>>
>>>raid). If you have 3 disks read speed increases and the
>>>
>>>
>>write speed is almost the
>>
>>
>>>same. Using ReiserFS I was able to resize 61G LV to 64G LV
>>>
>>>
>>without errors. With
>>
>>
>>>ext3 it worked, but fsck.ext3 had a lot of work to do (the
>>>
>>>
>>partition was ~50G full).
>>
>>
>>>I hope one day online resize will work with bouth and
>>>
>>>
>>reiserfs will get more stable
>>
>>
>>>with acl and SELinux support.
>>> http://www.aplawrence.com/Linux/lvm.html
>>> ps: putting the /boot partiton ouside the LVM worked fine for me.
>>>
>>>
>>>
>>>
>>>
>>okay - there are a few steps one needs to take to get their
>>system using
>>LVM. It can be tricky to get your brain around at first but
>>it will slot
>>into place. The steps are quite straight forward - even when
>>setting up
>>post install. Here's a brief overview. I'm assuming you can
>>follow the
>>man pages of each of the commands specified - there are a number of
>>options which will be up to you:
>>
>>as root
>>One(a): Make sure you have backed up any important data
>>before trashing
>>your system ;-)
>>One: make sure your kernel supports LVM (By default this is
>>supported in
>>FC1)
>>Two: create some LVM partitions (of type 8e under fdisk)
>>Three: reboot or execute partprobe
>>Four: execute vgscan
>>Five: use pvcreate to assign your newly typed disks as use
>>within the LVM
>>(actually, four and five might be back to front)
>>Six: use vgcreate to generate a new volume group (and add
>>some physical
>>volumes tro it)
>>Seven: use lvcreate to make your logical volume
>>Eight: format your new logical volume
>>
>>then it's up to you - mount as you like
>>
>>use e2fsadm to extend and reduce the size of the volume
>>
>>There is a huge amount of documentation and you should really get to
>>grips with resizing, adding new PVs etc. Before you start
>>putting useful
>>data on your new LV!
>>
>>
>
>
>Thanks for the info Neil. I think I do have a hang of it.. sort of anyway.
>So, what you're saying is that I have to create the LVM partition using
>fdisk
>1st before I can get to execute vgscan??
>
>Currently I just type vgscan and then it complains
>vgscan -- LVM driver/module not loaded??
>
>(it's loaded. The module is named dm-mod.ko right??)
>
>
>
>
>
>
you've got me there. It should be 'lvm-mod' that gets loaded. try a
manual 'modprobe lvm-mod'. If that works try running 'depmod' to setup
the module dependancies again. Sounds like something is missing the
mark. Create one or two partitions using fdisk and try vgscan again.
neil
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