关于看槽位的理解：
最近在 tsm 的虚拟带库上建了两个库，有发现：
TSM:TSM_SVR1> 
show slots vtl01
ANR2017I Administrator SERVER_CONSOLE issued command: show slots vtl01
PVR slot information for library VTL01.
Library          : VTL01 
Product Id       : Scalar i500      
Support module   : 2

Mount count      : 0

Drives           : 4 
Slots            : 4 
Changers         : 1 
Import/Exports   : 0

Device           : /dev/tsmscsi/lb0

Drive   0, element 2051 
Drive   1, element 2052 
Drive   2, element 2053 
Drive   3, element 2054

Changer 0, element 0

Slot 0, status Allocated, element number 1, barcode not present, barcode value <>, devT=ANY,
mediaT=-1, elemT=ANY
Slot 1, status Allocated, element number 2, barcode not present, barcode value <>, devT=ANY,
mediaT=-1, elemT=ANY
Slot 2, status Allocated, element number 3, barcode not present, barcode value <>, devT=ANY,
mediaT=-1, elemT=ANY
Slot 3, status Full, element number 4, barcode not present, barcode value <>, devT=ANY, mediaT=-1,
elemT=ANY

slot element range 1 - 4

发现上面slot3 和slot 0,1,2 的状态不一样，就是说一共4个槽位，vtl01 带库就占了3 个，
再结合：
看带库中的磁带：
TSM:TSM_SVR1> 
q libv
ANR2017I Administrator SERVER_CONSOLE issued command: QUERY LIBVOLUME

Library Name    Volume Name    Status              Owner         Last Use     Home       Device
                                                                              Element    Type  
------------    -----------    ----------------    ----------    ---------    -------    ------
VTL01           AD0001         Private                           Data         1                
VTL01           AD0002         Private                                        2                
VTL01           AD0003         Private                                        3                
VTL02           AD0004         Scratch                                        4

发现：vtl01 是占了3 个， vtl02 是只有一个：
再看一下 vtl02 的情况：
TSM:TSM_SVR1> 
show slots vtl02
ANR2017I Administrator SERVER_CONSOLE issued command: show slots vtl02
PVR slot information for library VTL02.
Library          : VTL02 
Product Id       : Scalar i500      
Support module   : 2

Mount count      : 0

Drives           : 4 
Slots            : 4 
Changers         : 1 
Import/Exports   : 0

Device           : /dev/tsmscsi/lb0

Drive   0, element 2051 
Drive   1, element 2052 
Drive   2, element 2053 
Drive   3, element 2054

Changer 0, element 0

Slot 0, status Full, element number 1, barcode not present, barcode value <>, devT=ANY, mediaT=-1,
elemT=ANY
Slot 1, status Full, element number 2, barcode not present, barcode value <>, devT=ANY, mediaT=-1,
elemT=ANY
Slot 2, status Full, element number 3, barcode not present, barcode value <>, devT=ANY, mediaT=-1,
elemT=ANY
Slot 3, status Allocated, element number 4, barcode not present, barcode value <>, devT=ANY,
mediaT=-1, elemT=ANY

slot element range 1 - 4

发现vt02 是占了第四个槽位。

还有就是会发现 
tsm:> q v 和tsm:> q libv 的磁带看到的不一样：
TSM:TSM_SVR1> 
q libv
ANR2017I Administrator SERVER_CONSOLE issued command: QUERY LIBVOLUME

Library Name     Volume Name     Status               Owner          Last Use      Home        Device
                                                                                   Element     Type  
------------     -----------     ----------------     ----------     ---------     -------     ------
VTL01            AD0001          Private                             Data          1                 
VTL01            AD0002          Private                                           2                 
VTL01            AD0003          Private                                           3                 
VTL02            AD0004          Scratch                                           4

TSM:TSM_SVR1>

Storage Management Server for Linux/i386 - Version 5, Release 5, Level 1.0

TSM:TSM_SVR1> 
q v
ANR2017I Administrator SERVER_CONSOLE issued command: QUERY VOLUME

Volume Name                  Storage         Device         Estimated       Pct      Volume 
                             Pool Name       Class Name      Capacity      Util      Status 
------------------------     -----------     ----------     ---------     -----     --------
/opt/tivoli/tsm/server/-     ARCHIVEPOOL     DISK               5.0 M       0.0     On-Line 
 bin/archive.dsm                                                                            
/opt/tivoli/tsm/server/-     BACKUPPOOL      DISK              10.0 M       0.0     On-Line 
 bin/backup.dsm                                                                             
AD0001                       BA_TAPE_PO-     LTO2               1.0 G       0.8     Filling 
                              OL                                                            
AD0002                       BA_TAPE_PO-     LTO2               0.0 M       0.0      Empty  
                              OL                                                            
AD0003                       AR_TAPE_PO-     LTO2               0.0 M       0.0      Empty  
                              OL                                                            
AS0001                       BA_T_POOL       LTO3               0.0 M       0.0      Empty  
AS0004                       BA_T_POOL       LTO3               0.0 M       0.0      Empty  
TT0003                       AR_TAPE_PO-     LTO2               0.0 M       0.0      Empty  
                              OL                                                            
TT0004                       AR_TAPE_PO-     LTO2               0.0 M       0.0      Empty  
                              OL                                                           
                              
发现只有贴了标签的磁带：就是被label 过的才是进带库的。
才是可用的。
q v 看到的是进入 spool 池的磁带，很多是不能用的。会报can not access 的。