1. mysqldump will only keep the connection open for as long as it
needs it. Once your calling script is allowed to continue mysqldump
has either exited successfully or with an error, but either way the
connection should no longer be active.
2. I don't think that would be a good idea. 30 minutes should buy you
enough time, but if the system is getting slammed or some other
unforeseeable event happens that makes the system slow down to a
crawl then you run the risk of breaking your backup process. The bulk
of the execution time in your script is almost certainly with your
tar command. The 'j' option is telling it to use the bzip2 algorithm
for compression, which is a very high compression level, but takes a
long time to obtain compared to other compression algorithms. In
short, I don't think anything that you're doing is going to cause any
data loss as long as mysqldump isn't locking the slave database for a
huge amount of time.
As an aside, this isn't really PHP related so much as it is MySQL or
even *nix shell commands related, you might try a MySQL list for
verification.
On Oct 3, 2006, at 10:29 AM, David Giragosian wrote:
Howdy Guys,
I have a PHP backup script running as a cronjob that has an exec
(mysqldump)
line followed a bit later by an exec(tar -cjf) line. The backup
script runs
against a slave db in the wee hours, and the master gets a
continuous stream
of inputs at the rate of about 18,720 per day. Obviously as the
database
grows in size, the script takes longer and longer to run. Right
now, after
about 15 months of operation, it's taking about 40 minutes to
complete. But
I did a test yesterday, and the mysqldump part only takes about 2
minutes to
finish.
Even though I've never lost data, my concern is that since master-
slave
syncing is blocked while the script runs, I just might lose
something if
there's a buffer overrun or something like that.
So, Question 1 is: does mysqldump's connection to the slave db
exist for the
entire script execution time, or just for the length of time of its
own
execution? I imagine if I used mysql_connect() in the script that
it would
be for the entire length of the script execution, but mysqldump
makes its
own connection, so I'm just not sure about this.
Question 2: Should I, just to be on the safe side, break out the
mysqldump
code into its own scipt, and run it, say, 30 minutes before the tar
script?
Thanks for your time,
David
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
