Steve Crawford wrote:
...I have a
cron job from the production database that runs every 5-10min to
check if there are any new archive logs and copy new archive logs to
the remote stand by failover machine.
The problem with this scenario is that there might be a possibility
that I might scp a partially filled archive log over to the remote
machine on a heavily updated databases with batch jobs runnings most
of the time like ours.
So, inorder to over come this we want to change the archive_command to
archive_command = 'cp %p /archives-temp/%f && mv /archives-temp/%f
/archives/%f'
( I could do remote copy also with the command but I dont want to go
that route because of network problems. )
....
My question is there any problem in using this approach ? will I run
into problems in the future ? are there any other better ways of
solving this problem ?
Looks like it should work but have you considered using rsync instead?
If the file grows from one pass to the next, rsync will send the
differences.
Given the small number of files (at least far fewer thatn the
half-million file trees my rsyncs process every 10 minutes) in the
archive directory, rsync will probably only take a fraction of a
second to determine whether or not any transfers are needed. I'll bet
that you could run rsync every 15 seconds with virtually no increase
in system load other than whatever is required to transfer the data
and you have that load already.
Rsync can also handle deleting files from the receiving end if you wish.
I am starting to work on a wal-shipping backup and I plan to try rsync
first.
Some advice. I make extensive use of rsync. The core skeleton of my
scripts goes something like this:
cd /the/appropriate/place
if [ -f rsync.lockfile ]
# Exit - new pass started before previously
# started rsync completed
exit
fi
date > rsync.lockfile
rsync <your parameters as appropriate>
rm rsync.lockfile
I run another script on the target machine that periodically checks
the age of rsync.lockfile and sends alerts if it is excessively old
(where excessive will be determined by the specifics of your setup - I
use one hour).
Cheers,
Steve
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Hi Steve,
Thanks! for the quick reply, I thought about rsync too, but wasnt
sure about completely how it handles partial files. I use rsync for all
the backups, it works fine for all the application except for our mail
application it copies the files but at the end of the job it gives me
message like
------------------------------------------------------------------------------------
send_files failed to open //this/file/ : No such file or directory
rsync error: some files could not be transferred (code 23) at main.c(1158)
------------------------------------------------------------------------------------
Considering it is copying all our mail messages and it takes a lot of
time to rsync the whole thing, there might be changes to the file or
file gets deleted completely from time it gets the files to rsync and do
the actual rsync.
Pallav.
