| /* |
| The compile-time configurable defaults for the Linux SCSI tape driver. |
| |
| Copyright 1995 Kai Makisara. |
| |
| Last modified: Wed Sep 2 21:24:07 1998 by root@home |
| |
| Changed (and renamed) for OnStream SCSI drives garloff@suse.de |
| 2000-06-21 |
| |
| $Header: /cvsroot/osst/Driver/osst_options.h,v 1.6 2003/12/23 14:22:12 wriede Exp $ |
| */ |
| |
| #ifndef _OSST_OPTIONS_H |
| #define _OSST_OPTIONS_H |
| |
| /* The minimum limit for the number of SCSI tape devices is determined by |
| OSST_MAX_TAPES. If the number of tape devices and the "slack" defined by |
| OSST_EXTRA_DEVS exceeds OSST_MAX_TAPES, the large number is used. */ |
| #define OSST_MAX_TAPES 4 |
| |
| /* If OSST_IN_FILE_POS is nonzero, the driver positions the tape after the |
| record been read by the user program even if the tape has moved further |
| because of buffered reads. Should be set to zero to support also drives |
| that can't space backwards over records. NOTE: The tape will be |
| spaced backwards over an "accidentally" crossed filemark in any case. */ |
| #define OSST_IN_FILE_POS 1 |
| |
| /* The tape driver buffer size in kilobytes. */ |
| /* Don't change, as this is the HW blocksize */ |
| #define OSST_BUFFER_BLOCKS 32 |
| |
| /* The number of kilobytes of data in the buffer that triggers an |
| asynchronous write in fixed block mode. See also OSST_ASYNC_WRITES |
| below. */ |
| #define OSST_WRITE_THRESHOLD_BLOCKS 32 |
| |
| /* OSST_EOM_RESERVE defines the number of frames are kept in reserve for |
| * * write error recovery when writing near end of medium. ENOSPC is returned |
| * * when write() is called and the tape write position is within this number |
| * * of blocks from the tape capacity. */ |
| #define OSST_EOM_RESERVE 300 |
| |
| /* The maximum number of tape buffers the driver allocates. The number |
| is also constrained by the number of drives detected. Determines the |
| maximum number of concurrently active tape drives. */ |
| #define OSST_MAX_BUFFERS OSST_MAX_TAPES |
| |
| /* Maximum number of scatter/gather segments */ |
| /* Fit one buffer in pages and add one for the AUX header */ |
| #define OSST_MAX_SG (((OSST_BUFFER_BLOCKS*1024) / PAGE_SIZE) + 1) |
| |
| /* The number of scatter/gather segments to allocate at first try (must be |
| smaller or equal to the maximum). */ |
| #define OSST_FIRST_SG ((OSST_BUFFER_BLOCKS*1024) / PAGE_SIZE) |
| |
| /* The size of the first scatter/gather segments (determines the maximum block |
| size for SCSI adapters not supporting scatter/gather). The default is set |
| to try to allocate the buffer as one chunk. */ |
| #define OSST_FIRST_ORDER (15-PAGE_SHIFT) |
| |
| |
| /* The following lines define defaults for properties that can be set |
| separately for each drive using the MTSTOPTIONS ioctl. */ |
| |
| /* If OSST_TWO_FM is non-zero, the driver writes two filemarks after a |
| file being written. Some drives can't handle two filemarks at the |
| end of data. */ |
| #define OSST_TWO_FM 0 |
| |
| /* If OSST_BUFFER_WRITES is non-zero, writes in fixed block mode are |
| buffered until the driver buffer is full or asynchronous write is |
| triggered. */ |
| #define OSST_BUFFER_WRITES 1 |
| |
| /* If OSST_ASYNC_WRITES is non-zero, the SCSI write command may be started |
| without waiting for it to finish. May cause problems in multiple |
| tape backups. */ |
| #define OSST_ASYNC_WRITES 1 |
| |
| /* If OSST_READ_AHEAD is non-zero, blocks are read ahead in fixed block |
| mode. */ |
| #define OSST_READ_AHEAD 1 |
| |
| /* If OSST_AUTO_LOCK is non-zero, the drive door is locked at the first |
| read or write command after the device is opened. The door is opened |
| when the device is closed. */ |
| #define OSST_AUTO_LOCK 0 |
| |
| /* If OSST_FAST_MTEOM is non-zero, the MTEOM ioctl is done using the |
| direct SCSI command. The file number status is lost but this method |
| is fast with some drives. Otherwise MTEOM is done by spacing over |
| files and the file number status is retained. */ |
| #define OSST_FAST_MTEOM 0 |
| |
| /* If OSST_SCSI2LOGICAL is nonzero, the logical block addresses are used for |
| MTIOCPOS and MTSEEK by default. Vendor addresses are used if OSST_SCSI2LOGICAL |
| is zero. */ |
| #define OSST_SCSI2LOGICAL 0 |
| |
| /* If OSST_SYSV is non-zero, the tape behaves according to the SYS V semantics. |
| The default is BSD semantics. */ |
| #define OSST_SYSV 0 |
| |
| |
| #endif |
