Re: [Bug-tar] record size = x blocks?

[Sergey Poznyakoff]

Hello,

To begin with, thanks to everybody for expressing their thoughts on
this matter, and apologies for my not being able to participate in the
discussion earlier.

Now, let me provide some background on the record size warning.
Historically, tar emitted a warning if the record size differed from the
expected value and the verbose level was > 1 (e.g. `tar -tv'). This kind
of warning is important for people using tape drives, as the proper
record size diagnostics allows them to adjust their drives for optimal
performance. 

This behavior was broken in tar 1.17, and it was not noticed until
Ed Leaver reported it in his mail:

  http://lists.gnu.org/archive/html/bug-tar/2007-09/index.html

(this posting also explains how and why the record size report is useful.)

When the problem was fixed, Ed drew my attention to the fact that,
being emitted in verbose levels > 1, this diagnostics is easily
obscured by the copious output tar usually produces in these levels.
After a bit of thought I decided to lower verbosity requirement by 1,
which behavior made its way into tar 1.21 and subsequent 1.22.

Now I can say that this was not the best decision, as the additional
diagnostics broke some testcases and scripts.  However, I am reluctant
to revert to the verbosity>1 requirement, due to the reason explained
above.  I feel that the --verbose semantics is not clear enough in this
context: using the same option to control detailed listing, produced on
stdout, and to control additional diagnostic messages on stderr does
not seem right to me.  I think that an additional option, similar to
gcc's -W, would be in place.  For example, `tar --warning=record' would
enable emitting the record size warning.

Opinions?

Regards,
Sergey