Managing Serviceguard Eighteenth Edition, September 2010

Table 3-4 Pros and Cons of Volume Managers with Serviceguard (continued)
TradeoffsAdvantagesProduct
• Requires purchase of additional
license
• Cannot be used for a cluster lock
• Does not support activation on
multiple nodes in either shared
mode or read-only mode
• May cause delay at package
startup time due to lengthy vxdg
import
• Disk group configuration from any
node.
• DMP for active/active storage devices.
• Supports exclusive activation.
• Hot relocation and unrelocation of failed
subdisks
• Supports up to 32 plexes per volume
• RAID 1+0 mirrored stripes
• RAID 1 mirroring
• RAID 5
• RAID 0+1 striped mirrors
• Supports multiple heartbeat subnets,
which could reduce cluster reformation
time.
Veritas Volume
Manager— Full
VxVM product
• Disk groups must be configured
on a master node
• Cluster startup may be slower than
with VxVM
• Requires purchase of additional
license
• No support for RAID 5
• CVM requires all nodes to have
connectivity to the shared disk
groups
• Not currently supported on all
versions of HP-UX
• Provides volume configuration
propagation.
• Supports cluster shareable disk groups.
• Package startup time is faster than with
VxVM.
• Supports shared activation.
• Supports exclusive activation.
• Supports activation in different modes
on different nodes at the same time
• RAID 1+0 mirrored stripes
• RAID 0+1 striped mirrors
• CVM versions 4.1 and later support the
Veritas Cluster File System (CFS)
Veritas Cluster
Volume Manager
Responses to Failures
Serviceguard responds to different kinds of failures in specific ways. For most hardware
failures, the response is not user-configurable, but for package and service failures,
you can choose the system’s response, within limits.
System Reset When a Node Fails
The most dramatic response to a failure in a Serviceguard cluster is an HP-UX TOC or
INIT, which is a system reset without a graceful shutdown (normally referred to in
this manual simply as a system reset). This allows packages to move quickly to another
node, protecting the integrity of the data.
A system reset occurs if a cluster node cannot communicate with the majority of cluster
members for the predetermined time, or under other circumstances such as a kernel
hang or failure of the cluster daemon (cmcld).
116 Understanding Serviceguard Software Components