Expert Oracle Exadata - Parent Directory

CHAPTER 9 RECOVERING EXADATAHere you can see that the make_cellboot_usb script copies over all of the storage cell software(cellbits), and configuration files (lastGoodConfig) it needs to recover the storage cell. Finally, you seethat the Grub boot loader is installed on the USB drive so you can boot the system from it. When thescript completes, you can remove the external USB disk from the system. This rescue disk can later beused for restoring your storage cell to working condition should the need arise.Active and Inactive System VolumesExadata has three modes for installing software: first time install, patch (or in-partition patch), and anout-of-partition upgrade. A journal of your installation history can be seen using the imagehistorycommand:> imagehistoryVersion : 11.2.1.2.3Image activation date : 2010-05-15 20:07:07 -0700Imaging mode: freshImaging status: successVersion : 11.2.1.2.6Image activation date : 2010-06-03 09:10:08 -0700Imaging mode: patchImaging status: success...Version : 11.2.2.2.0.101206.2Image activation date : 2010-12-17 11:45:17 -0600Imaging mode: out of partition upgradeImaging status: successThe -all option can be used to show much more detail about your software installation history.In-Partition PatchesAs discussed earlier, Exadata maintains two sets of system volumes, Active, and Inactive. In-partitionpatches are rare. But when an in-partition patch is performed, the patch is applied to the Active systemimage. Exadata saves a copy of the files and settings that were changed during the installation process soyou can back out the patch later if needed.Out-of-Partition UpgradesWhen an out-of-partition upgrade is performed, Exadata installs the software into the Inactive systemvolumes. If the installation fails, the cell will continue to boot from the current (Active) system image.This is how Exadata ensures that a failed upgrade does not cause an extended outage. If the upgradecompletes successfully, Exadata sets the upgraded volumes to Active status and changes the old Activevolumes to Inactive. It then updates the /boot/grub/grub.conf file with the device name of the newlyactivated root file system and reboots. During the boot process, the Grub boot loader reads thegrub.conf file to find the device it will use for mounting the root file system. A quick look at thegrub.conf file shows that our Active partition for the root file system is /dev/md6.> grep kernel /boot/grub/grub.conf | cut -c1-53 | head -1kernel /vmlinuz-2.6.18-194.3.1.0.3.el5 root=/dev/md6291