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-rw-r--r--Documentation/scsi/st.txt15
1 files changed, 14 insertions, 1 deletions
diff --git a/Documentation/scsi/st.txt b/Documentation/scsi/st.txt
index 40752602c050..691ca292c24d 100644
--- a/Documentation/scsi/st.txt
+++ b/Documentation/scsi/st.txt
@@ -2,7 +2,7 @@ This file contains brief information about the SCSI tape driver.
The driver is currently maintained by Kai Mäkisara (email
Kai.Makisara@kolumbus.fi)
-Last modified: Sun Feb 24 21:59:07 2008 by kai.makisara
+Last modified: Sun Aug 29 18:25:47 2010 by kai.makisara
BASICS
@@ -85,6 +85,17 @@ writing and the last operation has been a write. Two filemarks can be
optionally written. In both cases end of data is signified by
returning zero bytes for two consecutive reads.
+Writing filemarks without the immediate bit set in the SCSI command block acts
+as a synchronization point, i.e., all remaining data form the drive buffers is
+written to tape before the command returns. This makes sure that write errors
+are caught at that point, but this takes time. In some applications, several
+consecutive files must be written fast. The MTWEOFI operation can be used to
+write the filemarks without flushing the drive buffer. Writing filemark at
+close() is always flushing the drive buffers. However, if the previous
+operation is MTWEOFI, close() does not write a filemark. This can be used if
+the program wants to close/open the tape device between files and wants to
+skip waiting.
+
If rewind, offline, bsf, or seek is done and previous tape operation was
write, a filemark is written before moving tape.
@@ -301,6 +312,8 @@ MTBSR Space backward over count records.
MTFSS Space forward over count setmarks.
MTBSS Space backward over count setmarks.
MTWEOF Write count filemarks.
+MTWEOFI Write count filemarks with immediate bit set (i.e., does not
+ wait until data is on tape)
MTWSM Write count setmarks.
MTREW Rewind tape.
MTOFFL Set device off line (often rewind plus eject).