Veritas InfoScale™ 8.0 Virtualization Guide - Linux
- Section I. Overview of Veritas InfoScale Solutions used in Linux virtualization
- Overview of supported products and technologies
- About Veritas InfoScale Solutions support for Linux virtualization environments
- About Kernel-based Virtual Machine (KVM) technology
- About the RHEV environment
- Overview of supported products and technologies
- Section II. Implementing a basic KVM environment
- Getting started with basic KVM
- Veritas InfoScale Solutions configuration options for the kernel-based virtual machines environment
- Installing and configuring Cluster Server in a kernel-based virtual machine (KVM) environment
- Configuring KVM resources
- Getting started with basic KVM
- Section III. Implementing Linux virtualization use cases
- Application visibility and device discovery
- Server consolidation
- Physical to virtual migration
- Simplified management
- Application availability using Cluster Server
- Virtual machine availability
- Virtual machine availability for live migration
- Virtual to virtual clustering in a Red Hat Enterprise Virtualization environment
- Virtual to virtual clustering in a Microsoft Hyper-V environment
- Virtual to virtual clustering in a Oracle Virtual Machine (OVM) environment
- Disaster recovery for virtual machines in the Red Hat Enterprise Virtualization environment
- Disaster recovery of volumes and file systems using Volume Replicator (VVR) and Veritas File Replicator (VFR)
- Multi-tier business service support
- Managing Docker containers with InfoScale Enterprise
- About the Cluster Server agents for Docker, Docker Daemon, and Docker Container
- Managing storage capacity for Docker containers
- Offline migration of Docker containers
- Disaster recovery of volumes and file systems in Docker environments
- Application visibility and device discovery
- Section IV. Reference
- Appendix A. Troubleshooting
- Appendix B. Sample configurations
- Appendix C. Where to find more information
- Appendix A. Troubleshooting
Storage Savings from space-optimized snapshots
With the large number of virtual machines housed per physical server, the number of boot images used on a single server is also significant. A single bare-metal Linux boot image needs around 3 GB of space at a minimum. Installing software stacks and application binaries on top of that requires additional space typically resulting in using around 6 GB of space for each virtual machine that houses a database application.
When a user provisions a new virtual machine, the boot image can be a full copy or a space-optimized snapshot. Using a full copy results in highly inefficient use of storage. Not only is storage consumed to house identical boot images, storage is also consumed in making the boot images highly available (mirror across enclosures) as well in their backup.This large amount of highly available, high performance storage is very expensive, and likely to eliminate the cost advantages that server virtualization would otherwise provide. To add to it, backup and recovery of such capacity is also an expensive task.
In order to address the above issue, Veritas recommends the use of space-optimized snapshots of the gold image as boot images of the various VM guests. Space-optimized snapshots do not make a full copy of the data in the gold image, rather they work on the copy-on-write principle where only the changed blocks are stored locally. This set of changed blocks is called a Cache Object and it is stored in a repository for all such space-optimized snapshots, called the Cache Object Store, which is backed by physical storage. The Cache Object offers a significant storage space reduction, typically occupying a 5-20% storage footprint, relative to the parent volume (the gold image volume in this case). The same Cache Object Store can be used to store changed blocks for multiple snapshot volumes.
Each Snapshot held in the Cache Object Store contains only changes made to the gold image to support that installation's boot environment. Hence, to achieve the best possible storage reduction, install software on data disks rather than root file systems and limit as many changes as possible to the gold image operating files (i.e., system, hosts, passwd, etc.).