Veritas InfoScale™ 8.0.2 Solutions Guide - AIX
- Section I. Introducing Veritas InfoScale
- Section II. Solutions for Veritas InfoScale products
- Section III. Stack-level migration to IPv6 or dual stack
- Section IV. Improving database performance
- Overview of database accelerators
- Improving database performance with Veritas Quick I/O
- About Quick I/O
- Improving database performance with Veritas Cached Quick I/O
- Improving database performance with Veritas Concurrent I/O
- Section V. Using point-in-time copies
- Understanding point-in-time copy methods
- Backing up and recovering
- Preserving multiple point-in-time copies
- Online database backups
- Backing up on an off-host cluster file system
- Database recovery using Storage Checkpoints
- Backing up and recovering in a NetBackup environment
- Off-host processing
- Creating and refreshing test environments
- Creating point-in-time copies of files
- Section VI. Maximizing storage utilization
- Optimizing storage tiering with SmartTier
- Optimizing storage with Flexible Storage Sharing
- Optimizing storage tiering with SmartTier
- Section VII. Migrating data
- Understanding data migration
- Offline migration of native volumes and file systems to VxVM and VxFS
- Converting LVM volume groups to VxVM disk groups
- Conversion of JFS and JFS2 file systems to VxFS
- Conversion steps explained
- Examples of using vxconvert
- About test cases
- Converting LVM, JFS and JFS2 to VxVM and VxFS
- Online migration of native LVM volumes to VxVM volumes
- Online migration from LVM volumes in standalone environment to VxVM volumes
- Online migration from LVM volumes in VCS HA environment to VxVM volumes
- Online migration of a native file system to the VxFS file system
- Migrating a source file system to the VxFS file system over NFS v3
- VxFS features not available during online migration
- Migrating storage arrays
- Migrating data between platforms
- Overview of the Cross-Platform Data Sharing (CDS) feature
- CDS disk format and disk groups
- Setting up your system to use Cross-platform Data Sharing (CDS)
- Maintaining your system
- Disk tasks
- Disk group tasks
- Displaying information
- File system considerations
- Specifying the migration target
- Using the fscdsadm command
- Maintaining the list of target operating systems
- Migrating a file system on an ongoing basis
- Converting the byte order of a file system
- Section VIII. Veritas InfoScale 4K sector device support solution
Plan for new VxVM logical volume names
When you change from LVM volumes to VxVM volumes, the device names by which your system accesses data are changed. LVM creates device nodes for its logical volumes in /dev under directories named for the volume group. VxVM creates its device nodes in /dev/vx/dsk and /dev/vx/rdsk. When conversion is complete, the old LVM device nodes are gone from the system, and the system will access data on the device nodes in /dev/vx.
This change in names can present problems. Any application that refers to specific device node names will be at risk when these names change. Similarly, any files that record specific device node names for use by applications can be problematic.
The most obvious area where this problem arises is in the /etc/filesystems file. To handle this problem, vxconvert rewrites /etc/filesystems with the new VxVM names when conversion is complete so that fsck, mount, and related utilities will behave as they did prior to the conversion.
There are potentially many other applications, though, that may be put at risk by the name changes in conversion. vxconvert cannot help with these. The system administrator must examine the mechanisms used in each of the following areas to see if they reference LVM device names:
Databases run on raw logical devices may record the name of that device node.
Backup systems may do device level backups based on device node names recorded in private files. Also labelling of the backups may record device names.
Scripts run by cron(1M).
Other administrative scripts.
To work around the issue of the name changes in conversion, use the vxconvert mapping file. vxconvert records a mapping between the names of the LVM device nodes and VxVM device nodes. This data can be used to create symbolic links from the old LVM volume to the new VxVM device names. The mapping is recorded in the following file:
/etc/vx/reconfig.d/vgrecords/vol_grp_name/vol_grp_name.trans
This file provides information on how to proceed further to link the old LVM volume names to the new VxVM device names.
Warning:
This method of resolving the naming problem has risks. The symbolic links can become stale. For example, if a database refers to /dev/vx/rdsk/vol1 through a symbolic link /dev/rvol1("the old LVM name"), and if the underlying VxVM volume configuration is changed in any way, the database could refer to a missing or different volume.
Note:
You may want to use this symbolic link approach to ease the transition to VxVM. You can set up the symbolic links after the successful conversion to VxVM. Then, you can do the investigation on a case by case basis for each volume. When you are satisfied that there are no problems introduced by the name change, the symbolic link to that volume can be removed. You must be careful to maintain a static VxVM volume configuration during this transition period.
Over time, the ultimate goal should be that the underlying VxVM naming is used by all applications, and that there are no indirect references to those volumes.