If this was covered in previous notes, sorry, but I didn't see it, and
I've been out for a few days so I didn't get into this at the beginning.

In Red Hat (and probably Suse too), there's a chicken-egg problem.  The
DASD driver gets its list of valid devices from a parm that's passed to
the driver in /etc/modprobe.conf.  But at the time the module is loaded,
the running root filesystem is the initrd.  The regular root filesystem
can't be mounted till AFTER the dasd driver is loaded.  You only need to
make the initrd if you change the list of devices.  

We coded a list of placeholder device numbers in our base configuration
going out to dasdzz, so we don't have to fiddle going forward.  Note
that this list is ONLY devices that are visible automatically at boot
time, and reserves the device node assignments for them.  Additional
devices outside the range can be added later via attach and chccwdev,
and device nodes will be built starting after the list built from the
parameter.  (i.e., if modprobe.conf contains 100-10F, that reserves
dasda-dasdp, even if some of them don't exist, and the first dynamically
added disk will be dasdq.)

As far as bare metal goes, we did try some tests in a bare LPAR, and it
works fine with thousands of devices visible, but it takes a LONG time
to scan them all.  Also, at the time we tested, there was some quirk
with coding the actual devices in modprobe.conf, and filtering that way
caused the system to hang coming up.  It might have been an error in
configuration somewhere, we were on a schedule, so we simply removed the
filter, and brought it up seeing all devices.  

-----Original Message-----
From: Linux on 390 Port [mailto:[email protected]] On Behalf Of
Ivan Warren
Sent: Thursday, February 19, 2009 9:37 AM
To: [email protected]
Subject: Re: [LINUX-390] Why does one need to mkinitrd/zipl ? (WAS :
Broken logical volume group)

Richard Troth wrote:
> Ivan ... hear this:
> With SLES10, unless you are changing something about the root FS, you
> do not need to re-stamp your INITRD.  It is exactly as you say it
> should be.
>
>
> -- R;   <><
>
>
That's good enough for me ;)

At least the idea that I would have gave me fodder for a tantrum :P

--Ivan

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