Expert Oracle Exadata - Parent Directory

CHAPTER 9 RECOVERING EXADATAWhen the backup is finished, you should check the error file, enkdb01_system_backup.stderr, for anyissues logged during the backup. If you are satisfied with the backup, you can unmount and drop thesnapshots. You will create a new set of snapshots each time you run a backup. After you copy the backupimage off to tape you can optionally unmount and drop the temporary partition you created to store it.[root@enkdb01 snap]# cd /[root@enkdb01 /]# umount /mnt/snap/u01[root@enkdb01 /]# rmdir /mnt/snap/u01[root@enkdb01 /]# umount /mnt/snap[root@enkdb01 /]# rmdir /mnt/snap[root@enkdb01 /]# lvremove /dev/VGExaDb/root_snapDo you really want to remove active logical volume root_snap? [y/n]: yLogical volume "root_snap" successfully removedroot@enkdb01 /]# lvremove /dev/VGExaDb/u01_snapDo you really want to remove active logical volume u01_snap? [y/n]: yLogical volume "u01_snap" successfully removed[root@ricudb01 /]# lvremove /dev/VGExaDb/sysbackDo you really want to remove active logical volume sysback? [y/n]: yLogical volume "sysback" successfully removed[root@enkdb01 /]# umount /mnt/sysback[root@enkdb01 /]# rmdir /mnt/sysback[root@ricudb01 /]# lvremove /dev/VGExaDb/sysbackDo you really want to remove active logical volume sysback? [y/n]: yLogical volume "sysback" successfully removedAs discussed in the opening paragraph, early models of Exadata V2 did not implement LVM formanaging file system storage. Without LVM snapshots, getting a clean system backup would requireshutting down the applications on the server (including the databases), or purchasing third-partybackup software. Even then, there would be no way to create a backup in which all files are consistentwith the same point in time. LVM snapshots fill an important gap in the Exadata backup and recoveryarchitecture and offer a simple, manageable strategy for backing up the database servers. Later in thischapter we’ll discuss how these backups are used for restoring the database server when file systems arelost or damaged.Backing Up the Storage CellThe first two disks in a storage cell contain the Linux operating system. These Linux partitions arecommonly referred to as the system volumes . Backing up the system volumes using industry standardLinux backup software is not recommended. So how do you back up the system volumes? Well, theanswer is that you don’t. Exadata automatically does this for you through the use of an internal USBdrive called the CELLBOOT USB flash drive. If you are the cautious sort, you can also create your own cellrecovery image using an external USB flash drive. In addition to the CELLBOOT USB flash drive, Exadataalso maintains, on a separate set of disk partitions, a full copy of the system volumes as they were beforethe last patch was installed. These backup partitions are used for rolling back a patch. Now let’s take alook at how these backup methods work.287