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
General information regarding conversion speed
Factors affecting conversion speed include:
Size of volume groups. The larger the volume groups, the larger the VGRA area on each disk. A copy must be made of the VGRA area of each physical disk. Some areas are greater than 64MB; therefore a 50-disk volume requires 64MB reads and writes (that is, 100 large I/O requests) to complete. Some volume groups have 128 disks.
Individual size of a logical volume in a volume group, and the complexity of the logical volume layout. For example, for a system with 50 9GB drives, a simple 50GB logical volume can be created using 6 disks. But a 50GB striped logical volume that takes the first 1GB of all 50 disks can also be created. The first and simple logical volume takes less time to convert than the striped volume since only 5 disks need to be checked for metadata. However, for the striped volume, 50 disks need to be checked and 50 VGRAs to be copied. In addition, the complexity of reproducing the VxVM commands to set up the striped volumes requires more VxVM commands to be generated to represent more smaller subdisks representing the same amount of space.
Another factor in converting stripes is that stripes create more work for the converter. In some cases, stripes require 1GB volume, although only the metadata is being changed. In other cases, where there are more physical disks in one volume than another, there is more metadata to deal with. The converter has to read every physical extent map to ensure there are no holes in the volume; if holes are found, the converter maps around them.
Number of volumes. While it takes longer to convert one 64GB volume than one 2GB volume, it also takes longer to convert 64 1GB volumes than one 64GB volume, providing that the volumes are of similar type.
Mirrored volumes. Mirrored volumes typically do not take more time to convert than simple volumes. Volumes that are mirrored and striped at the same time would take longer.
Currently, after conversion, mirrored volumes are not automatically synchronized because a large mirror could take hours to complete.
For example, in tests, a 150 GB volume group consisting of 20 simple logical volumes takes approximately 35-40 minutes to convert. In contrast, the same volume group (150GB) consisting of mirrored volumes that need to be synchronized can take 30-40 hours to convert.
Note:
If you convert mirrored volumes, you must synchronize them in a separate step.