PSP installation adds entries in grub.conf

by HP Pro on ‎02-02-2012 12:19 PM

Question

New entries in grub.conf have beeen added by PSP install test on a test server. It also changed the default boot to the latest (entry no.4).

Questions:

  1. Why they're there
  2. Can I remove them and set the default to the default Red Hat kernel?  (I just tested a kernel upgrade and it set it back to default=0 (default RH kernel)
  3. Is it documented somewhere?

Here are the entries:

 

# This entry (no. 2) added by Proliant HBA install script
# in package cpq_cciss-3.6.28-15.rhel5
title HP-2.6.18-274.el5
        root (hd0,0)
        kernel /vmlinuz-2.6.18-274.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet
        initrd /HP-initrd-2.6.18-274.el5.img


# This entry (no. 3) added by Proliant HBA install script
# in package hpahcisr-1.2.6-9.rhel5
title HP-2.6.18-274.el5-0
        root (hd0,0)
        kernel /vmlinuz-2.6.18-274.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet
        initrd /HP-initrd-2.6.18-274.el5.img-0


# This entry (no. 4) added by Proliant HBA install script
# in package mptlinux-4.00.13.09-6.rhel5
title HP-2.6.18-274.el5-1
        root (hd0,0)
        kernel /vmlinuz-2.6.18-274.el5 ro root=/dev/VolGroup01/LogVol00 rhgb quiet
        initrd /HP-initrd-2.6.18-274.el5.img-1

Answer

When a storage driver that controls your system disk(s) is updated, the updated driver must be included in the initrd file. Otherwise the old version of the driver will still be used to mount your root filesystem... which will obviously make it (effectively) impossible to unload the old driver without rebooting the system.

 

The HP storage driver update packages don't check if the driver that is being updated is in fact required to mount the root filesystem, since complexities like software RAID or LVM might mislead an automated check. Therefore, HP has chosen that the update packages will always create a new initrd and a new set of boot options, just to be safe.

 

This is not unique to HP updates: any storage driver updates that are not integrated in the RedHat kernel must do the same, if they need to replace the driver that runs the system disk.

 

If your system runs fine with the RedHat kernel, you can skip the storage driver packages if the features/optimizations provided by them are not necessary to you. Eventually the equivalent driver versions tend to end up being included in the RedHat standard kernel packages.

 

However, there is one big exception to that:

If your hardware includes a Smart Array B110i, you will need the hpahcisr driver package. Without it, the system will treat the B110i controller as a standard non-RAID AHCI SATA controller. Since that's exactly what the physical hardware is. The B110i is a software/BIOS-based RAID, which only uses a metadata format that is compatible with its bigger SmartArray E and P series brothers. All modern Linux distributions include a basic AHCI controller driver, and will automatically use it on the B110i unless the hpahcisr package is installed and the proper procedures have been followed.

 

May be RedHat regards the hpahcisr driver as a simple duplication of the Linux software RAID functionality, and probably won't include it in their distribution. May be RedHat would rather see the Smart Array metadata support included in (an extended version of) the dmraid utility, which reads various software/BIOS RAID metadata formats and implements a compatible RAID setup using tried-and-true Linux software RAID routines. That would make the hpahcisr driver unnecessary.

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