Cameron Simpson wrote:
On 09Mar2007 03:03, Mike McCarty <Mike.McCarty@xxxxxxxxxxxxx> wrote:
| Cameron Simpson wrote:
| >Maybe:
| > tar Af tarfile more-files...
|
| Time comparisons, for exact same backup...
|
| tar Af 0:52:07
| gzip 0:28:52
| total 1:20:59
|
| tar cz 0:24:49
[...]
| Doesn't look all that efficient to me. Perhaps doing separate
| tar and then using "r" will be better. But note that the compression
| alone took longer than both tarring and compressing in one step.
Yeah. "tar czf" works by piping through a gzip, so it's faster than "tar cf
That's not the cause, I'm sure. For example, adding /usr/src, which is
48 KB (i.e. I deleted it, and only the directory structure remains) took
two minutes. I looked carefully at the behavior, and it appears that
tar reads the entire archive to find the EOF.
...; gzip ..." because the separate gzip is reading from the disc ad writing
to the disc at the same time. The first one is reading from, ideally, another
disc.
No, that's not it.
[snip]
Presuming the latter, why not use one tar?
A plain "tar cf tarfile" or "tar czf tarfile.gz" will be nice and silent and
That's the way it works now. I don't want silence, I want progress
reports of the top level directories.
[snip]
Regarding progress reporting, "tar cvf" reports nicely but interleaves any
error message with the TOC, which is annoying and also hides the errors. I
I don't want to watch the xterm it's running in. I want a wall.
have a suggestion for this, which is a little tacky but may work quite
nicely:
>tarfile
This line looks like a syntax error to me. What is it
supposed to accomplish?
tar cf tarfile ... &
tarpid=$!
tailpid=`
exec 3>&1 1>&2
( tail -f tarfile 3>&- &
echo $! >&3
) | ( exec 3>&-; tar tvf - | cat >/dev/tty ) &
`
wait # ... for the "tar cf"
kill $tailpid # kill the tail
[snip]
The "cat >/dev/tty" is for demo purposes, writing the TOC to the terminal. Do
as you wish. Grepping for '/$' lists just the directories, for example.
Umm, two points. (1) Having one process writing and another reading
the same archive results in a "chase", eating lots of resources
while the reader tries to catch up with the writer. (2) I don't
want a detailed report, I want a progress report so I can know
approx. how much has been done.
[snip]
How far does that go towards solving your problem?
I sure appreciate the effort. I don't want a detailed TOC.
I generate that while verifying that the backup looks
intact, and put that on the last CDROM. Just a little
bit every once in a while to let me know how far it's
gotten.
Mike
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