git: ffaf862df662 - main - Mention that SILI makes tcopy(1) slow on modern tape drives

The branch main has been updated by phk:

URL: https://cgit.FreeBSD.org/src/commit/?id=ffaf862df662d507e8dd2667bffcba91e3745fe6

commit ffaf862df662d507e8dd2667bffcba91e3745fe6
Author:     Poul-Henning Kamp <phk@FreeBSD.org>
AuthorDate: 2024-09-03 10:44:20 +0000
Commit:     Poul-Henning Kamp <phk@FreeBSD.org>
CommitDate: 2024-09-03 10:44:20 +0000

    Mention that SILI makes tcopy(1) slow on modern tape drives
---
 usr.bin/tcopy/tcopy.1 | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/usr.bin/tcopy/tcopy.1 b/usr.bin/tcopy/tcopy.1
index da6a5231a843..f608e0af07e4 100644
--- a/usr.bin/tcopy/tcopy.1
+++ b/usr.bin/tcopy/tcopy.1
@@ -97,6 +97,16 @@ command appeared in
 .Sh BUGS
 .Bl -item
 .It
+Modern tape drives may return a SCSI "Incorrect Length Indicator (ILI)"
+for reach read with a different block size that what is on the
+tape, and that slows things down a lot.
+This can be disabled with the
+.Xr mt 1
+command:
+.Bd -literal -offset indent
+$ mt param sili -s 1
+.Ed
+.It
 Writing an image of a tape to a file does not preserve much more than
 the raw data.
 Block size(s) and tape EOF marks are lost which would