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Diffstat (limited to 'Documentation/ide/ide-tape.txt')
| -rw-r--r-- | Documentation/ide/ide-tape.txt | 65 |
1 files changed, 0 insertions, 65 deletions
diff --git a/Documentation/ide/ide-tape.txt b/Documentation/ide/ide-tape.txt deleted file mode 100644 index 3f348a0b21d8..000000000000 --- a/Documentation/ide/ide-tape.txt +++ /dev/null @@ -1,65 +0,0 @@ -IDE ATAPI streaming tape driver. - -This driver is a part of the Linux ide driver. - -The driver, in co-operation with ide.c, basically traverses the -request-list for the block device interface. The character device -interface, on the other hand, creates new requests, adds them -to the request-list of the block device, and waits for their completion. - -The block device major and minor numbers are determined from the -tape's relative position in the ide interfaces, as explained in ide.c. - -The character device interface consists of the following devices: - -ht0 major 37, minor 0 first IDE tape, rewind on close. -ht1 major 37, minor 1 second IDE tape, rewind on close. -... -nht0 major 37, minor 128 first IDE tape, no rewind on close. -nht1 major 37, minor 129 second IDE tape, no rewind on close. -... - -The general magnetic tape commands compatible interface, as defined by -include/linux/mtio.h, is accessible through the character device. - -General ide driver configuration options, such as the interrupt-unmask -flag, can be configured by issuing an ioctl to the block device interface, -as any other ide device. - -Our own ide-tape ioctl's can be issued to either the block device or -the character device interface. - -Maximal throughput with minimal bus load will usually be achieved in the -following scenario: - - 1. ide-tape is operating in the pipelined operation mode. - 2. No buffering is performed by the user backup program. - -Testing was done with a 2 GB CONNER CTMA 4000 IDE ATAPI Streaming Tape Drive. - -Here are some words from the first releases of hd.c, which are quoted -in ide.c and apply here as well: - -| Special care is recommended. Have Fun! - -Possible improvements: - -1. Support for the ATAPI overlap protocol. - -In order to maximize bus throughput, we currently use the DSC -overlap method which enables ide.c to service requests from the -other device while the tape is busy executing a command. The -DSC overlap method involves polling the tape's status register -for the DSC bit, and servicing the other device while the tape -isn't ready. - -In the current QIC development standard (December 1995), -it is recommended that new tape drives will *in addition* -implement the ATAPI overlap protocol, which is used for the -same purpose - efficient use of the IDE bus, but is interrupt -driven and thus has much less CPU overhead. - -ATAPI overlap is likely to be supported in most new ATAPI -devices, including new ATAPI cdroms, and thus provides us -a method by which we can achieve higher throughput when -sharing a (fast) ATA-2 disk with any (slow) new ATAPI device. |