ленточное устройство SCSI (SCSI tape device)
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.
