4.0.0 HP Polyserve Matrix Server Administration Guide (T5392-96052, March 2010)

• Journaling and live crash recovery. Filesystem metadata operations are written
to a journal before they are performed. If a server using the filesystem should
crash during an operation, the journal is replayed and any journaled operations
in progress at the time of the crash are completed. Users on other servers will
experience only a slight delay in filesystem operations during the recovery.
Matrix Server databases
Matrix Server uses the following databases to store cluster information:
• Shared Memory Data Store (SMDS). The SANPulse process stores filesystem status
information in this database. The database contains cp_status and sp_status
files that are located in t%SystemDrive%\Program Files\Polyserve\
MatrixServer\conf on each server. These files should not be changed.
• Device database. Matrix Server uses a device database to store the physical UID
and a global device identifier for each disk imported into the matrix. The database
is located on the membership partitions that you selected when installing Matrix
Server. The membership partitions are also used for functions related to SAN
control.
• Volume database. This database stores information about dynamic volumes and
is located on the membership partitions.
• mxds datastore. This database stores cluster configuration information and is
located on the membership partitions.
Virtual hosts and failover protection
Matrix Server uses virtual hosts to provide failover protection for servers and network
applications.
A virtual host is a hostname/IP address configured on one or more servers. The
network interfaces selected on those servers to participate in the virtual host must be
on the same subnet. One server is selected as the primary server for the virtual host.
The remaining servers are backups.
The primary and backup servers do not need to be dedicated to these activities; all
servers can support other independent functions.
To ensure the availability of a virtual host, Matrix Server monitors the health of all
network interfaces and the health of the underlying server. If you have created service
or device monitors, those monitors periodically check the health of the specified
services or devices. If any of these health checks fail, Matrix Server can transfer the
virtual host to a backup server and the network traffic will continue.
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