HP Serviceguard Extended Distance Cluster for Linux A.01.01 Deployment Guide, Third Edition, May 2008

Configuring your Environment for Software RAID
Configuring the Legacy Package Control Script and RAID Configuration File
Chapter 3 77
Editing the raid.conf File
The raid.conf file specifies the configuration information of the RAID
environment of the package. You must place a copy of this file in the
package directory of every package that you have enabled Software
RAID. The parameters in this file are:
• RPO_TARGET
Given a set of storage that is mirrored remotely, as in Figure 1-4, the
RPO_TARGET (Recovery Point Objective Target) is the maximum time
allowed between the expiration of the Link_Down_Timeout (t1 in
Figure 3-1, after the failure of the data links to the remote storage)
and the package starting up on the remote node (t4 on Figure 3-1). If
more time elapses than what is specified for RPO_TARGET, the
package is prevented from starting on the remote node (assuming
that the node still has access only to its own half of the mirror).
By default, RPO_TARGET is set to 0. Leave it at 0 to ensure the
package does not start on an adoptive node with a mirror half that is
not current. This ensures the highest degree of data currency.
If RPO_TARGET is not set to 0, the value of RAID_MONITOR_INTERVAL
should be less than the value of RPO_TARGET.
(RAID_MONITOR_INTERVAL should also be less than the value of the
Link_Down_Timeout parameter so that disk access failure can be
recognized early enough in certain failure scenarios.)
IMPORTANT A very low value of RAID_MONITOR_INTERVAL (less than 5 seconds)
has some impact on system performance because of the high
frequency of polling.
You can also set RPO_TARGET to the special value -1 or to any positive
integer. Setting RPO_TARGET to -1 causes the RAID system to ignore
any time-window checks on the disk set. This allows the package to
start with a mirror half that is not current.
Setting the RPO_TARGET to any positive integer, means that the
package will start with a mirror half that is not current by any
number of seconds less than that value. For example, an RPO_TARGET
of 45 means that the package will start only if the mirror is up to
date, or out of date by less than 45 seconds.