IBM System Storage DS4000, Hardware Manual

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Chapter 7. Advanced maintenance, troubleshooting, and diagnostics
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WE-RO Write Exclusive - Registrants Only: Writes exclusive: All registered
host ports may write to the logical drive. Reads shared: Any host
port may read from the logical drive.
EA-RO Exclusive Access - Registrants Only: Only registered host ports
may read from or write to the logical drive.
WE-AR Write Exclusive - All Registrants: Writes exclusive: All registered
host ports may write to the logical drive. Reads shared: Any host
port may read from the logical drive.
EA-AR Exclusive Access - All Registrants: Only a host port may read from
or write to the logical drive.
PTPL Shows Yes if the registrations are set to persist through a power loss.
To view the registrations that are associated with the logical drive reservation, either
double-click the desired logical drive, or highlight the logical drive and check the View
Associated Registrations check box in the upper left of the dialog. The following information
is then presented:
Interface type Shows the type of interface: SATA, SAS, or Fibre.
Host (initiator) port Shows the associated user label for the particular host port. If
the host port alias has not been provided, then Not Available
appears.
Associated host Shows the host associated with the specific logical drive.
Controller (target) ports Shows the port name of the target port.
Holds Reservation? Shows either Yes or No, depending on whether the specific
host port is the reservation holder.
Clearing persistent reservations
Sometimes it is not possible to clear the persistent reservation from the host. This is the case
if a cluster host had been decommissioned without being shut down cleanly. Any persistent
reservations prevent the associated logical drives from being deleted or changed in any way.
There is an option to clear the logical drive reservations from the Storage Manager
Subsystem Management window by selecting Advanced

Maintenance

Persistent
Reservations.
1. In the upper-left corner of the Persistent Reservations window, make sure that the View
Associated Registrations check box is cleared.
2. Click one or more desired logical drives. To select all of the logical drives, click Select All.
3. Click Clear.
4. In the text box in the Clear Registrations/Reservations dialog, type yes, and click OK. If
you do not want to clear any reservations, click Cancel to return to the Persistent
Reservations dialog.
The reservation and registrations that were associated with the logical drives that you
highlighted in the upper pane are now cleared.
Target reset
It is normal to see TGT Reset events logged in the Major Event Log (MEL) during a host
cluster failover. A support call will need to be logged for any unexplained target reset events.