Understanding and Designing Serviceguard Disaster Recovery Architectures

• multiple power cords
• online addition or replacement of I/O cards, memory
special device file The device file name that the HP-UX operating system gives to a single connection to a node, in
the format /dev/devtype/filename.
split-brain
syndrome
When a cluster reforms with equal numbers of nodes at each site, and each half of the cluster
thinks it is the authority and starts up the same set of applications, and tries to modify the same
data, resulting in data corruption. Serviceguard architecture prevents split-brain syndrome in all
cases unless dual cluster locks are used.
SRDF (Symmetrix Remote Data Facility) A level 1-3 protocol used for physical data replication between
EMC Symmetrix disk arrays.
SVOL A secondary volume configured in an XP series disk array that uses Continuous Access. SVOLs
are the secondary copies in physical data replication with Continuos Access on the XP.
SymCLI The Symmetrix command line interface used to configure and manage EMC Symmetrix disk
arrays.
Symmetrix device
number
The unique device number that identifies an EMC logical volume.
synchronous data
replication
Each data replication I/O waits for the preceding I/O to complete before beginning another
replication. Minimizes the chance of inconsistent or corrupt data in the event of a rolling disaster.
T
transaction
processing monitor
(TPM)
Software that enables you to modify an application to store in-flight transactions in an external
location until that transaction has been committed to all possible copies of the database or
filesystem, therefore it ensures completion of all copied transactions. A TPM protects against data
loss at the expense of the CPU overhead involved in applying the transaction in each database
replica.
Software that provides a reliable mechanism to ensure that all transactions are successfully
committed. A TPM may also provide load balancing among nodes.
transparent
failover
A client application that automatically reconnects to a new server without the user taking any
action.
transparent IP
failover
Moving the IP address from one network interface card (NIC), in the same node or another node,
to another NIC that is attached to the same IP subnet so that users or applications may always
specify the same IP name/address whenever they connect, even after a failure.
U-Z
volume group In LVM, a set of physical volumes such that logical volumes can be defined within the volume
group for user access. A volume group can be activated by only one node at a time unless you
are using Serviceguard OPS Edition. Serviceguard can activate a volume group when it starts a
package. A given disk can belong to only one volume group. A logical volume can belong to
only one volume group.
WAN data
replication
solutions
Data replication that functions over leased or switched lines.
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