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ленточное устройство SCSI (SCSI tape device)

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Примечание (Note)

1.  When exchanging data between systems, both systems have to
           agree on the physical tape block size.  The parameters of a
           drive after startup are often not the ones most operating
           systems use with these devices.  Most systems use drives in
           variable-block mode if the drive supports that mode.  This
           applies to most modern drives, including DATs, 8mm helical
           scan drives, DLTs, etc.  It may be advisable to use these
           drives in variable-block mode also in Linux (i.e., use
           MTSETBLK or MTSETDEFBLK at system startup to set the mode),
           at least when exchanging data with a foreign system.  The
           drawback of this is that a fairly large tape block size has
           to be used to get acceptable data transfer rates on the SCSI
           bus.

2. Many programs (e.g., tar(1)) allow the user to specify the blocking factor on the command line. Note that this determines the physical block size on tape only in variable- block mode.

3. In order to use SCSI tape drives, the basic SCSI driver, a SCSI-adapter driver and the SCSI tape driver must be either configured into the kernel or loaded as modules. If the SCSI-tape driver is not present, the drive is recognized but the tape support described in this page is not available.

4. The driver writes error messages to the console/log. The SENSE codes written into some messages are automatically translated to text if verbose SCSI messages are enabled in kernel configuration.

5. The driver's internal buffering allows good throughput in fixed-block mode also with small read(2) and write(2) byte counts. With direct transfers this is not possible and may cause a surprise when moving to the 2.6 kernel. The solution is to tell the software to use larger transfers (often telling it to use larger blocks). If this is not possible, direct transfers can be disabled.