HiCommand Dynamic Link Manager (HDLM) for Windows Systems User's Guide (HIT5201-96001, January 2008)

34 Chapter 2 HDLM Functions
#4: When the following conditions are satisfied, a path that has been determined to have an
intermittent error also becomes subject to automatic failback:
– All the paths connected to an LU are Online(E), Offline(E), or Offline(C).
– All the paths connected to an LU have been determined to have an intermittent
error.
– The processing of continuous I/O operations issued to an LU is successful.
#5: During reservation processing for an LU, the Offline(E) status is temporarily changed to
Offline(P). When the reservation processing finishes, the Offline(P) status is changed to
Offline(C).
#6: When the following conditions are satisfied, the connected Offline(E) paths are
automatically placed online:
– All the online paths are Online(E) and SCSI devices connected to the Online(E) paths
have been deleted.
– The Offline(E) paths are assumed to have had an intermittent error, and are
excluded from automatic failback.
– The SCSI devices are connected to the Offline(E) paths.
The last available online path for each LU cannot be placed offline by using the Path
Management window or by executing the offline operation. This ensures access to the LU.
For details on the offline operation, see section
7.4.
If an error occurs in the last available online path for each LU, the status of the path is
changed to Online(E).
If you are using automatic failback, when the path recovers from an error, HDLM
automatically places the path online. However, there are the following exceptions:
 When you are using intermittent error monitoring, the path in which the intermittent
error occurred is not automatically placed online when the path recovers from the error.
In such a case, place the path online manually. If the only online path is Online(E)
when the path is recovered from the error, the path might be placed online
automatically. For details, see
Figure 2.13.
 There is a case in which the path is automatically placed online even if you are not using
the automatic failback function. If you remove the hardware that supports the Windows
plug and play function, HDLM places the path offline. Then, HDLM automatically places
the path back online when the hardware is re-installed. However, this applies only when
there is no other cause for the path being placed offline. Since HDLM automatically
places the path online without using the automatic failback function, you do not need to
place the path online manually.
When you use the LU dynamic deletion functionality, the path whose status is Online(E) is
deleted. Therefore, the path whose status is Online(E) is not displayed in the Path
Management window. Also, the view operation does not display the path whose status is
Online(E).