small question about tape-based dumps

[Tim Judd]

On 10/17/09, Stevan Tiefert <stevan-tiefert at kabelmail.de> wrote:
> Am Samstag, den 17.10.2009, 18:49 -0600 schrieb Tim Judd:
>> On 10/17/09, Jerry McAllister <jerrymc at msu.edu> wrote:
>> <snip>
>>
>> > You do not need to. dump alrady writes that when it finishes each time.
>> > If you to that, you will get a second one at that location.
>> >
>> > You do not need to do the rewind and mt fsf between each dump.  I just
>> > do it to make it very clear to myself in my scripts what I am expecting
>> > and that I am doing it right.
>> >
>> > ////jerry
>>
>> <snip>
>>
>> If dump is the tool for tapes, and tar is named after tape archives...
>
> Please, no flamewar!!!

Wasn't planning on starting one.  Sorry if it came across that way.

>
>> Do both of these utilities write the *proper* EOF to whatever medium
>> it's writing to?
>
> They both write EOF.
>
>> I bring this up, because dump can also write to a file on a formatted
>> FS.  Does the file end with this same EOF?  What does tar do?
>
> There is only one EOF: The EOF.
>
>
>> Why have a mt weof function if it's useless?  I'm loosing the logic in
>> this one, trying to make sure things work as they should.  I admit
>> tapes on bsd are so foreign to me, I might as well be speaking
>> $another-language.
>
> weof is not useless. There are some file operations without writing an
> EOF, like streams or something like that, but tar and dump are writing
> with an EOF at the end of files :-)


So it's a item for "good measure" rather than an item "as necessity"
in creating backups.

Thanks for all the info.  I'm happy knowing more.


--Tim