Veritas InfoScale™ 8.0 Virtualization Guide - Linux
- Section I. Overview of Veritas InfoScale Solutions used in Linux virtualization
- Overview of supported products and technologies
- Overview of the Veritas InfoScale Products Virtualization Guide
- About Veritas InfoScale Solutions support for Linux virtualization environments
- About Kernel-based Virtual Machine (KVM) technology
- About the RHEV environment
- Virtualization use cases addressed by Veritas InfoScale products
- About virtual-to-virtual (in-guest) clustering and failover
- Overview of supported products and technologies
- Section II. Implementing a basic KVM environment
- Getting started with basic KVM
- Creating and launching a kernel-based virtual machine (KVM) host
- RHEL-based KVM installation and usage
- Setting up a kernel-based virtual machine (KVM) guest
- About setting up KVM with Veritas InfoScale Solutions
- Veritas InfoScale Solutions configuration options for the kernel-based virtual machines environment
- Dynamic Multi-Pathing in the KVM guest virtualized machine
- Dynamic Multi-Pathing in the KVM host
- Storage Foundation in the virtualized guest machine
- Enabling I/O fencing in KVM guests
- Storage Foundation Cluster File System High Availability in the KVM host
- Dynamic Multi-Pathing in the KVM host and guest virtual machine
- Dynamic Multi-Pathing in the KVM host and Storage Foundation HA in the KVM guest virtual machine
- Cluster Server in the KVM host
- Cluster Server in the guest
- Cluster Server in a cluster across virtual machine guests and physical machines
- Installing Veritas InfoScale Solutions in the kernel-based virtual machine 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
- About storage to application visibility using Veritas InfoScale Operations Manager
- About Kernel-based Virtual Machine (KVM) virtualization discovery in Veritas InfoScale Operations Manager
- About Red Hat Enterprise Virtualization (RHEV) virtualization discovery in Veritas InfoScale Operations Manager
- About Microsoft Hyper-V virtualization discovery
- Virtual machine discovery in Microsoft Hyper-V
- Storage mapping discovery in Microsoft Hyper-V
- Server consolidation
- Physical to virtual migration
- Simplified management
- Application availability using Cluster Server
- About application availability options
- Cluster Server In a KVM Environment Architecture Summary
- VCS in host to provide the Virtual Machine high availability and ApplicationHA in guest to provide application high availability
- Virtual to Virtual clustering and failover
- I/O fencing support for Virtual to Virtual clustering
- Virtual to Physical clustering and failover
- Recommendations for improved resiliency of InfoScale clusters in virtualized environments
- 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
- About disaster recovery for Red Hat Enterprise Virtualization virtual machines
- DR requirements in an RHEV environment
- Disaster recovery of volumes and file systems using Volume Replicator (VVR) and Veritas File Replicator (VFR)
- Configure Storage Foundation components as backend storage
- Configure VVR and VFR in VCS GCO option for replication between DR sites
- Configuring Red Hat Enterprise Virtualization (RHEV) virtual machines for disaster recovery using Cluster Server (VCS)
- Multi-tier business service support
- Managing Docker containers with InfoScale Enterprise
- About managing Docker containers with InfoScale Enterprise product
- 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
- Limitations while managing Docker containers
- Application visibility and device discovery
- Section IV. Reference
- Appendix A. Troubleshooting
- Troubleshooting virtual machine live migration
- Live migration storage connectivity in a Red Hat Enterprise Virtualization (RHEV) environment
- Troubleshooting Red Hat Enterprise Virtualization (RHEV) virtual machine disaster recovery (DR)
- The KVMGuest resource may remain in the online state even if storage connectivity to the host is lost
- VCS initiates a virtual machine failover if a host on which a virtual machine is running loses network connectivity
- Virtual machine start fails due to having the wrong boot order in RHEV environments
- Virtual machine hangs in the wait_for_launch state and fails to start in RHEV environments
- VCS fails to start a virtual machine on a host in another RHEV cluster if the DROpts attribute is not set
- Virtual machine fails to detect attached network cards in RHEV environments
- The KVMGuest agent behavior is undefined if any key of the RHEVMInfo attribute is updated using the -add or -delete options of the hares -modify command
- RHEV environment: If a node on which the VM is running panics or is forcefully shutdown, VCS is unable to start the VM on another node
- Appendix B. Sample configurations
- Appendix C. Where to find more information
- Appendix A. Troubleshooting
VirtIO disk drives
VirtIO is an abstraction layer for paravirtualized hypervisors in Kernel-based Virtual Machine (VM) technology. Unlike full virtualization, VirtIO requires special paravirtualized drivers running in each VM guest. VirtIO provides support for many devices including network devices and block (disk) devices. Using VirtIO to export block devices to a host allows files, VxVM volumes, DMP meta-nodes, SCSI devices or any other type of block device residing on host to be presented to the VM guest. When SCSI devices are presented to a VM guest using VirtIO, in addition to simple reads and writes, SCSI commands such as SCSI inquiry commands can be performed allowing VxVM in the guest to perform deep device discovery. Running VxVM and DMP in the host and the VM guest provides for consistent naming of SCSI devices from the array, to the host through to the VM guest.
Veritas InfoScale Solutions 8.0 supports VirtIO SCSI devices and VirtIO block devices with Linux KVM. virtio-scsi is a new virtual SCSI HBA interface. It is the foundation of an alternative storage implementation for virtual machines, replacing virtio-blk on Red Hat Enterprise Linux (RHEL) with improved scalability and providing standard SCSI command set support.
VirtIO features:
Dynamically adding devices:
VirtIO disk devices can be both added and removed from a running VM guest dynamically, without the need of a reboot.
VirtIO limitations:
Disk caching:
When disks are exported to the VM guest with the cache enabled, the VxVM configuration changes may get cached on the KVM host and not be applied to the disks. When disks are shared between more than one VM guest, such a configuration change is not visble from other VM guest systems than the one which made the change. To avoid potential configuration conflict, caching the host must be disabled (cache=no) while exporting the disks.
SCSI Commands:
SCSI devices that are presented as VirtIO devices to a VM guest support a limited subset of the SCSI command set. The KVM hypervisor blocks the restricted commands.
PGR SCSI-3 Reservations:
PGR SCSI-3 reservations are not supported on VirtIO block devices. To use SCSI-3 PR operations inside the KVM guest operating system, Veritas recommends that you use virtio-scsi to export SCSI devices to the guest. This limitation is applicable to releases prior to RHEL 6.4.
DMP Fast Recovery with SCSI devices:
DMP Fast Recovery bypasses the normal VirtIO read/write mechanism, performing SCSI commands directly against the device. If DMP Fast Recovery is used within the VM guest, caching in the host must be disabled (cache=none), to avoid data integrity issues.
Thin Reclamation:
Thin reclamation is not supported on VirtIO devices. The 'WRITE-SAME' command is blocked by the hypervisor. This limitation may be removed in future releases of Linux.
Resizing devices:
Linux does not support online disk resizing of VirtIO devices. To re-size a VirtIO device the VM guest must be fully shut down and re-started. Support for online re-sizing of block devices is under evaluation for Linux.
Maximum number of devices:
virtio-blk currently has a per-guest limitation of 32 devices. This device limitation includes all VirtIO devices, such as network interfaces and block devices. The device limitation is a result of the current VirtIO implementation where each device acts as a separate PCI device. virtio-scsi solves this limitation by multiplexing numerous storage devices on a single controller. Each device on a virtio-scsi controller is represented as a logical unit, or LUN. The LUNs are grouped into targets. The device limit per target is much larger; each device can have a maximum of 256 targets per controller and 16,384 logical units per target. You can use virtio-scsi instead of virtio-blk to use more than 32(28) disk devices inside the KVM guest.
VxFS:
In a KVM environment under heavy I/O load, data corruption may occur on VxFS file systems created on LUNs attached as VirtIO block devices. Please refer Red Hat Support Case #00945974 for more details: