Is lvmcreate_initrd expected to work?

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

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.

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

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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

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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