Keep the following recommendations in mind:

• You must install Veritas Volume Manager 5.1 or later with the FMR license and the Site Awareness license.

• Do not bring the DiskGroupSnap resource online in the SystemZone where the application service group is online.

• Make sure that the firedrill service group and the application service group both use the same values for the SystemZones attribute.

• Do not use Volume resources in the firedrill service group. The DiskGroupSnap agent internally uses the vxvol command to start all the volumes in the firedrill disk group.

• In large setups, you may need to tweak the various timer values so that the timers do not time out while waiting for VxVM commands to complete. The timers you need to tweak are the OfflineTimeout for the DiskGroupSnap resource and MonitorInterval and ActionTimeout for the associated DiskGroup resource, for example:

  # haconf  - makerw
  # hares -override dgsres OfflineTimeout
  # hares -modify dgsres OfflineTimeout 600
  # hares -override dgres MonitorInterval
  # hares -modify dgres MonitorInterval 1200 (this has to be twice
  		the value intended for ActionTimeout below)
  # hares -override dgres ActionTimeout
  # hares -modify dgres ActionTimeout 600
  # haconf  - dump  - makero

• When you create the firedrill service group, in general use the same attribute values that you use in the application service group.

  The BlockDevice attribute of the Mount resource changes between the application service group and the firedrill service group. In the BlockDevice path, you must append an _fd to the disk group name portion, for example,

  /dev/vx/dsk/newdg1/newvol1 becomes /dev/vx/dsk/newdg1_fd/newvol1.

  See Figure: Sample resource values for a DiskGroupSnap resource. shows the changes to resource values for the firedrill service group; note that the Volume resource is not included.

• Before commencing the fire drill, make sure that all the sites registered in the application DiskGroup are in ACTIVE state.