3PAR InForm® OS 2.2.4 Concepts Guide (320-200085 Rev B, March 2009)

B.4
Preserved Data
3PAR InForm OS Concepts Guide InForm OS Version 2.2.4
B.3 Preserved Data
When the InServ storage system is holding data in cache but is not able to write that data to
the destination disk for any reason, it saves the data to the preserved data logical disk. As
described in Logical Disk Types on page 2.6, this logical disk is automatically created at the
time that the storage system is installed and initially configured.
Preserved data, data written to the preserved data logical disks, is typically created due to a
temporary loss of availability of disks, a situation that usually corrects itself once the disks
become available again. When the destination logical disks become available again, the system
automatically plays back the preserved data by writing it from the preserved data LDs to the
destination logical disks.
If you notice that the preserved data logical disk has some data saved for a long time, use the
showpd
command to see which physical disks are not valid. If any disks are shown as
Missing
, it is necessary to take corrective action in order to make those disks available again.
When you notice persistent preserved data saved to the preserved data logical disk, contact
your local service provider for technical support and services.
B.4 Active and Inactive Hosts
■ An active host is a host that is connected to an InServ Storage Server port and recognized
by the InForm OS. Under normal operation, an active host may have a number of volumes
exported to it and can therefore access those volumes.
■ An inactive host is a host that is known to the InForm OS but is not recognized as being
connected to any InServ Storage Server port at the moment. This may be because the host is
currently disconnected from the storage server port, or due to an error condition such as
link failure or because the host is offline.
When a host on an InServ Storage Server port disappears for any reason, the following
happens:
1 The InForm OS recognizes that the host is missing on the port and changes the state of the
host from active to inactive.
2 The InForm OS remembers all volumes exported to the host before it became inactive. It
will not unexport the volumes on the port with the missing host.