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From Stefan Klein <st.fankl...@gmail.com>
Subject Re: Faster one-time replication doing file-system copy?
Date Tue, 18 Mar 2014 12:48:46 GMT
Hi,

from my understanding which might be wrong

2014-03-18 13:31 GMT+01:00 Daniel Gonzalez <gonvaled@gonvaled.com>:

> Thanks Dave,
>
> Yes, I understand that I need to restart it. Actually, I assume that both
> source and destination must be stopped while copying:
> - source to avoid data changes while copying, which can lead to
> inconsistent data being copied
>

A couchdb datafile is never inconsistent.
see https://wiki.apache.org/couchdb/How_to_make_filesystem_backups


> - destination to avoid that two processes (cp and couchdb) are stepping on
> each writing on the same files.
>

That's not how filehandles work (at least on Linux)
open 4 terminals
terminal 1:
cd /tmp
cat > file
terminal 2:
tail -f /tmp/file
terminal 1:
enter some text
terminal 3:
rm /tmp/file
cat > /tmp/file
terminal 4:
tail -f /tmp/file
terminal 1:
enter some text
terminal 3:
enter some text


as long the filehandle is not closed and re-opened it reads and writes to
the "old" file, although the "old" file doesn't have a directory entry
anymore.

So it should be fine to just copy over the file and post to _restart after
the copy finished.

regards,
Stefan

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