[linux-lvm] Is lvmcreate_initrd expected to work?

[linux-lvm] Is lvmcreate_initrd expected to work?

[Lars Kellogg-Stedman]

Now that we've solved the pressing oh-my-goodness-my-system-won't-boot 
problem, I've got a few other questions.

The lvm package comes with the nifty lvmcreate_initrd command...but in 
my experience it simply doesn't work.  While it's especially clever 
about resolving library dependencies, it seems to ignore the issue of 
kernel modules.

For instance, I'm running a "reasonably" stock RedHat/SGI 7.2 
installation, which means that both SCSI support and the RAID5 module 
are built as drivers.  This means that my initrd needs, minimally:

  - scsi_mod
  - sd_mod
  - xor
  - raid5
  - lvm-mod

And unfortunately, lvmcreate_initrd doesn't pick up on any of this.

I ended up custom building an initrd around busybox, which provides a 
flexible pre-boot environment, including access to a shell prompt from 
within the initrd (which proved extremely useful recently).  But 
obviously, not everybody is going to have the time or experience to do this.

I realize that the root-on-LVM design is fairly bleeding-edge, as these 
things go, but it is in the FAQ.  I suppose the best solution would be 
for distribution vendors such as RedHat to include LVM support in their 
own dist-specific 'mkinitrd' type script.

While it would probably be easier to build a custom kernel with all the 
necessary drivers built in, I'll probably stick with this solution now 
since I'm fond of my initrd.  What are other folks doing?

-- Lars

Re: [linux-lvm] Is lvmcreate_initrd expected to work?

[Goetz Bock]

On Tue, Nov 27 '01 at 17:56, Lars Kellogg-Stedman wrote:
> I ended up custom building an initrd around busybox, which provides a 
> flexible pre-boot environment, including access to a shell prompt from 
> within the initrd (which proved extremely useful recently).  But 
> obviously, not everybody is going to have the time or experience to do this.
Could you share some details about your cusrom initrd setup?

I tried to do the same, but always have problmes with 
- executing a shell
- continuing boot afterwards

Thanks,
    Goetz.

Re: [linux-lvm] Is lvmcreate_initrd expected to work?

[Lars Kellogg-Stedman]

> Could you share some details about your cusrom initrd setup?

Goetz,

I've added a section to my LVM web page at
<http://larsshack.freeservers.com/lvm/> detailing my initrd
configuration.

If you (or anyone else) has questions about the information there, feel
free to email me.

-- Lars


=====
lars@larsshack.org

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Re: [linux-lvm] Is lvmcreate_initrd expected to work?

[Patrick Caulfield]

On Tue, Nov 27, 2001 at 05:56:13PM -0500, Lars Kellogg-Stedman wrote:
> Now that we've solved the pressing oh-my-goodness-my-system-won't-boot 
> problem, I've got a few other questions.
> 
> The lvm package comes with the nifty lvmcreate_initrd command...but in 
> my experience it simply doesn't work.  While it's especially clever 
> about resolving library dependencies, it seems to ignore the issue of 
> kernel modules. 

Yes it does ignore the issue of kernel modules. It's quite hard for 
lvmcreate_initrd to know just which modules are needed to get the system booted,
though I suppose it's possible.

It is recommended that you build the kernel with the drivers needed to mount the
root partition compiled in, rather than as modules. I realise this goes against
the Red Hat methodology of having everything as a module.

patrick

Re: [linux-lvm] Is lvmcreate_initrd expected to work?

[Theo Van Dinter]

On Thu, Nov 29, 2001 at 09:05:08AM +0000, Patrick Caulfield wrote:
> Yes it does ignore the issue of kernel modules. It's quite hard for 
> lvmcreate_initrd to know just which modules are needed to get the system booted,
> though I suppose it's possible.

It could do the same thing as mkinitrd does by default (approx):
        - check if SCSI drivers are needed (scsi_hostadapter lines in
          modules.conf), if so add them to initrd and make sure to
          preload scsi_mod and sd_mod.
	- check the current lvm configuration, and if any of the pv's are MD
	  devices, pre-load the appropriate raid[0145] module as well (can
	  determine via /proc/mdstat).

Alternatively, options for specifying modules would work too. :)

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