When the drive has 2 ports, Oracle recommends that Host Application treat the second SL150 drive port as a fail over port. The library may report a CHECK CONDITION to a command received on one port, when the other port is already busy with a library command. When a host application receives either of the following new CHECK CONDITIONs, it should reissue the command:
Not Ready, Logical Unit Offline (02/04/12h)
Aborted Command, Logical Unit Communication Failure (0Bh/08/00)
No Sense, Operation in Progress (00/00/16h)
LUN 0 is used to communicate with the tape drive.
LUN 1 is used to communicate with the SL150 library.
The administrator for the SL150 Modular Tape Library can chose one of the following two drive element addressing modes. The mode chosen affects the way SCSI element addresses are reported over the library SCSI interface.
Setting the mode to Address All Drive Slots results in the following:
All drive slots (empty or installed) are reported to the host application over the library SCSI interface. Using this mode allows for the addition of new tape drives without restarting the library.
Each drive and empty drive bay is assigned a drive SCSI Element Address. Drive element addresses are assigned sequentially starting at 500 for each partition from the topmost drive in the partition to the bottom drive in the partition. Similarly, for non-partitioned libraries, drive element address are also assigned sequentially starting at 500 from the top of the library to the bottom of the library.
A SCSI MODE SENSE command requesting the Element Address Assignment page will end in Good status. The total number of data transfer elements reported will include empty drive bays.
A SCSI READ ELEMENT STATUS command that includes an empty drive slot will end in Good status. The Data Transfer Element Descriptor data for the empty drive slot will return the ED bit set to 1 (disabled) and an exception condition indicating an Empty Drive Bay; the Except Bit will be set to 1, the ASC field will be set to 3Bh, and the ASCQ field will be set to 1Ah.
A SCSI MOVE command from an empty drive slot will end in Check Condition Status. The sense data will indicate Illegal Request, Source Empty (Sense Key = 5h, ASC = 3Bh, ASCQ = 0Eh).
A SCSI MOVE command to an empty drive slot will end in Check Condition Status. The sense data will indicate Illegal Request, Empty Drive Bay (Sense Key = 5h, ASC = 3Bh, ASCQ = 1Ah).
A SCSI POSITION TO ELEMENT command to an empty drive slot will end in Good Status. The robot will move in front of the empty drive bay.
Setting the mode to Address Installed Drives Only results in the following:
Only drives present at initialization are reported to a host application over the library SCSI interface. If a new drive is added, the library must be rebooted before the new drive can be used by a host application.
Each installed drive is assigned a drive SCSI Element Address during library initialization. Drive element addresses are assigned sequentially starting at 500 for each partition from the topmost drive in the partition to the bottom drive in the partition. Similarly, for non-partitioned libraries, drive element address are also assigned sequentially starting at 500 from the top of the library to the bottom of the library.
A SCSI MODE SENSE command requesting the Element Address Assignment page will end in Good status. The total number of data transfer elements reported will include only the number of drives found to be present at initialization.
If a drive is removed, a SCSI READ ELEMENT STATUS command for the now empty drive slot will end in Good status. The Data Transfer Element Descriptor data for the empty drive slot will return the ED bit set to 1 (disabled) and an exception condition indicating a Tape Drive error; the Except Bit will be set to 1, the ASC field will be set to 40h, and the ASCQ field will be set to 02h.
The library supports unit reserve, release, and persistent reserve commands. Host software should reserve resources whenever possible.
The library does not maintain a separate "prevent" or "allow" state for each initiator. There is a single state for all initiators. Therefore, if any initiator sends a Prevent Medium Removal command, the library locks the CAPs. If any initiator sends an Allow Media Removal command, the library unlocks the CAPs. For more information, see "Prevent/Allow Medium Removal (1Eh)".
Host timeout values for SCSI commands may require adjustment based on the configuration of the library.
The library supports the following reservation management methods:
Reserve and Release — defined by the ANSI SCSI-3 Primary Commands (SPC-2) Standard. See Table 2-1 for command reservation restrictions.
Persistent Reservation — defined by the ANSI SCSI-3 Primary Commands (SPC-3) Standard. See Table 2-2 for command reservation restrictions.
Table 2-1 and Table 2-2 use the following definitions:
Conflict — The library terminates the command with a Reservation Conflict (18h) status.
Allowed — The library executes the command normally.
The library returns 0 for the Compatible Reservation Handling (CRH) bit in the Persistent Reserve In (5Eh) Report Capabilities Data page.
A CRH value of 0 indicates the library processed the reserve or release command as defined in SPC-2. Therefore, the library will return a Reservation Conflict (18h) when it receives a reserve or release command from the same initiator that holds the persistent reservation.
Table 2-1 Action when the Library is Reserved by Another Initiator
| Command | HP Bridged Drive | IBM Bridged Drive |
|---|---|---|
|
Initialize Element Status (07h) |
Conflict |
Conflict |
|
Initialize Element Status w/Range (37h) |
Conflict |
Conflict |
|
Inquiry (12h) |
Allowed |
Allowed |
|
Log Sense (4Dh) |
Allowed |
Allowed |
|
Mode Select (15h/55h) |
Conflict |
Conflict |
|
Mode Sense (1Ah/5Ah) |
Conflict |
Allowed |
|
Move Medium (A5h) |
Conflict |
Conflict |
|
Persistent Reserve In (5Eh) |
Conflict |
Conflict |
|
Persistent Reserve Out (5Fh) |
Conflict |
Conflict |
|
Position to Element (2Bh) |
Conflict |
Conflict |
|
Prevent/Allow Media Removal (1Eh) |
Prevent = 0, Allowed Prevent = 1, Conflict |
Prevent = 0, Allowed Prevent = 1, Conflict |
|
Read Element Status (B8h) |
Conflict |
Conflict |
|
Release (17h) |
AllowedFoot 1 |
AllowedFootref 1 |
|
Report LUNs (A0h) |
Allowed |
Allowed |
|
Report Target Port Groups (A3h) |
Allowed |
Allowed |
|
Request Sense (03h) |
Allowed |
N/AFoot 2 |
|
Request Volume Element Address (B5h) |
Conflict |
Allowed |
|
Reserve (16h) |
Conflict |
Conflict |
|
Send Diagnostics (1Dh) |
Conflict |
Conflict |
|
Send Volume Tag (B6h) |
Conflict |
Conflict |
|
Test Unit Ready (00h) |
Conflict |
Conflict |
Footnote 1 The reservation is not released.
Footnote 2 The Report Target Port Group command is not supported by the IBM drive.
Table 2-2 Persistent Reservation Command Restrictions when the Library is Reserved by Another Initiator
| Command | Non-Registered InitiatorFoot 1 | Registered Initiator: Exclusive Access ReservationFoot 2 | Registered Initiator: Exclusive Access Registrant Only Foot 3 |
|---|---|---|---|
|
Initialize Element Status (07h) |
Conflict |
Conflict |
Allowed |
|
Initialize Element Status w/Range (37h) |
Conflict |
Conflict |
Allowed |
|
Inquiry (12h) |
Allowed |
Allowed |
Allowed |
|
Log Sense (4Dh) |
Allowed |
Allowed |
Allowed |
|
Mode Select (15h/55h) |
Conflict |
Conflict |
Allowed |
|
Mode Sense (1Ah/5Ah) |
Conflict |
Conflict |
Allowed |
|
Move Medium (A5h) |
Conflict |
Conflict |
Allowed |
|
Persistent Reserve In (5Eh) |
Allowed |
Allowed |
Allowed |
|
Persistent Reserve Out (5Fh) - SA=Register |
Allowed |
Allowed |
Allowed |
|
Persistent Reserve Out (5Fh) - SA=Reserve |
Conflict |
Conflict |
Conflict |
|
Persistent Reserve Out (5Fh) - SA=Release |
Conflict |
AllowedFoot 4 |
AllowedFootref 4 |
|
Persistent Reserve Out (5Fh) - SA=Clear |
Conflict |
Allowed |
Allowed |
|
Persistent Reserve Out (5Fh) - SA=Preempt |
Conflict |
Allowed |
Allowed |
|
Persistent Reserve Out (5Fh) - SA=Preempt/Abort |
Conflict |
Allowed |
Allowed |
|
Persistent Reserve Out (5Fh) - SA=Register and Ignore |
Allowed |
Allowed |
Allowed |
|
Persistent Reserve Out (5fh) - SA=Resister and Move |
Conflict |
Conflict |
Conflict |
|
Position to Element (2Bh) |
Conflict |
Conflict |
Allowed |
|
Prevent/Allow Media Removal (1Eh) Prevent = 0 |
Allowed |
Allowed |
Allowed |
|
Prevent/Allow Media Removal (1Eh) Prevent = 1 |
Conflict |
Conflict |
Allowed |
|
Read Element Status (B8h) HP Drive |
Conflict |
Conflict |
Allowed |
|
Read Element Status (B8h) IBM Drive |
Allowed |
Allowed |
Allowed |
|
Release (17h) |
Conflict |
Conflict |
Allowed |
|
Report LUNs (A0h) |
Allowed |
Allowed |
Allowed |
|
Report Target Port Groups (A3h)Foot 5 |
Allowed |
Allowed |
Allowed |
|
Request Sense (03h) |
Allowed |
Allowed |
Allowed |
|
Request Volume Element Address (B5h) |
Conflict |
Conflict |
Allowed |
|
Reserve (16h) |
Conflict |
Conflict |
Allowed |
|
Send Diagnostics (1Dh) |
Conflict |
Conflict |
Allowed |
|
Send Volume Tag (B6h) |
Conflict |
Conflict |
Allowed |
|
Test Unit Ready (00h) HP Drive |
Allowed |
Allowed |
Allowed |
|
Test Unit Ready (00h) IBM Drive |
Conflict |
Conflict |
Allowed |
Footnote 1 Action when a non-registered initiator sends a command to a library reserved by another initiator.
Footnote 2 Action when a registered initiator sends a command to a library reserved by another initiator that has an Exclusive Access reservation.
Footnote 3 Action when a registered initiator sends a command to a library reserved by another initiator that has an Exclusive Access Registrant Only reservation.
Footnote 4 The reservation is not released.
Footnote 5 HP Drive Only. The Report Target Port Group command is not supported by the IBM drive
When a server is started, it discovers attached devices and assigns SCSI target and LUN IDs. It is possible for these SCSI assignments to change between restarts. Some operating systems do not guarantee that devices will always be allocated the same SCSI target ID after restarting. Also, some software depends on this association, so you do not want it to change.
The issue of SCSI ID assignment is addressed by persistent binding. Persistent binding is a host bus adapter (HBA) function that allows a subset of discovered targets to be bound between a server and device.
Implemented by a WWNN or WWPN, persistent binding causes a tape drive's WWN to be bound to a specific SCSI target ID.
See the SL150 Library Guide for more information.