Memo





Please follow the steps below to determine what is going wrong:

1.  Rewind the tape:

Command Descriptor block:
0000: 01 00 00 00 00 00

2.  Run a mode select to partition the tape into two equal sized
partitions:

Command Descriptor block:
0000: 15 11 00 00 5C 00

0000: 00 00 10 08 34 00 00 00 00 00 02 00 11 4E 17 01
0010: 30 01 00 00 27 00 FF FF 00 00 00 00 00 00 00 00
0020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0050: 00 00 00 00 00 00 00 00 00 00 00 00

3.  Run a mode sense to check the partitioning

Command Descriptor block:
0000: 1A 00 11 00 FF 00

0000: 5B 73 10 08 34 00 00 00 00 00 02 00 11 4E 17 01
0010: 30 01 00 00 27 0C 27 0C 00 00 00 00 00 00 00 00
0020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0050: 00 00 00 00 00 00 00 00 00 00 00 00

Below is my interpretation of the data returned by mode select (page
0x11)

Mode Sense Header List
----------------------
Medium type: 73
Write protect: 0
Buffered mode: 1
Tape speed: 0

Mode Sense Block Descriptor List
--------------------------------
Tape density code: 34
Block size: 512

Page code: 0x11
Page Definition: Medium Partition page (1)
Maximum number of additional partitions: 23
Additional partitions defined: 1
Partition size units (in MB): 2
Partition <0> Size: 9996
Partition <1> Size: 9996

-----------------------------------------------------------------
At this point, it would appear that the tape is correctly partitioned
-----------------------------------------------------------------

4.  Use mode sense to check for the active partition:

Command Descriptor block:
0000: 1A 00 10 00 FF 00

0000: 1B 73 10 08 34 00 00 00 00 00 02 00 90 0E 00 00
0010: 00 00 00 00 70 00 18 00 00 00 00 00

Active Partition: 0

5.  Write data to active partition (0)

cd  /directory1
tar  cvf  /dev/rct0 .

6.  Verify tape contents:

tar  tvf  /dev/rct0

< The data verified correctly >

7.  Use the locate command to move to partition #1 (from partition 0)

Command Descriptor block:
0000: 2B 02 00 00 00 00 00 00 01 00

8.  Use mode sense to check for the active partition:

Command Descriptor block:
0000: 1A 00 10 00 FF 00

0000: 1B 73 10 08 34 00 00 00 00 00 02 00 90 0E 00 01
0010: 00 00 00 00 70 00 18 00 00 00 00 00

Active Partition: 1

------------------------------------------------------------------
At this point, it would appear that a write would go to partition #1
I understand that you can also use 'mode select <page 0x10> to
change active partitions, but based on the data above, it looked like
the change to partition #1 worked
------------------------------------------------------------------

9.  Write data to active partition (1)

cd  /directory2
tar  cvf  /dev/rct0 .

10.  Use mode sense to check for the active partition:

Command Descriptor block:
0000: 1A 00 10 00 FF 00

0000: 1B 73 10 08 34 00 00 00 00 00 02 00 90 0E 00 00
0010: 00 00 00 00 70 00 18 00 00 00 00 00

Active Partition: 0

----------------------------------------------------------
This puzzles me.  Why did the partition revert back to 0??
----------------------------------------------------------

11.  Use the locate command to move to partition #1 (from partition 0)

Command Descriptor block:
0000: 2B 02 00 00 00 00 00 00 01 00

12.  Use mode sense to check for the active partition:

Command Descriptor block:
0000: 1A 00 10 00 FF 00

Active Partition: 1

13.  Verify the contents of the tape

tar  tvf  /dev/rct0

< The data verified correctly as directory2 >

14.  Verify the active partition

Command Descriptor block:
0000: 1A 00 10 00 FF 00

Active Partition: 0

----------------------------------------------------------------
This puzzles me again.  Why did the partition revert back to 0??
----------------------------------------------------------------

15.  Verify the data

tar cvf /dev/rct0

- The data is the contents of directory2

Summary:

- Even though it appears that I can create two partitions (see mode
sense 0x11 above), and that I can locate to the correct partition (see
mode sense 0x10 above), I can't write data to each partition.
- I would suspect that the UNIX driver is forcing partition 0 each time
and that I never do write to partition #0?


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