Tony Abernethy wrote:
With the usual caveats of "Your Mileage May Vary", this may give you an
idea of how far you can push things and get away with it.
In practice, I back up production MySQL databases when they are running.
Not that big a deal.
Some notes on improving the odds (of getting away with it):
One logical rsync is two rsyncs back-to-back.
The first one to "do all the work"
The second one to catch anything that changed during the first.
This still leaves a window of expsure, but it is fairly small.
If the rsync is over internet (or WAN) links,
a local rsync to a staging area and the long slow rsync from something
"stable".
This is with straight MyISAM tables. I would expect trouble from
anything with "transactional integrity".
With MyISAM, things are simple enough so that even if you catch
somehting in mid-something, its actually pretty hard to trash the table.
That's hard, not impossible. Actually with staged backups, it's pretty
well impossible to actually do yourself in.
The only time I've gotten bit (that I'm aware of) is the .MYD and the
.MYI out of sync and adding a new record and getting bit because the
autoincrement record already existed. Actually more funny than serious.
If you have only the primary and one backup (just one backup seems a
recipe for disaster, anyway), you will need to stop the database and do
the rsync. (And what do you do when the primary fails DURING the rsync?)
Backing up from Windows, my guess is that you will have better luck
doing an smb mount and doing the rsync from something unixy to something
unixy. With windows, a file opened normally will have EVERYTHING ELSE
locked out of doing anything with that file. With things unixy, it is
considered kosher to delete a file while someone else is writing it, the
standard sequence of an update is to ./configure; make; make install.
Then to shut down the old running program and bring up the new program.
The smb mount and unix rsync will NOT overcome the Windows semantics,
but should at least do as much as can be done. Windows likes to go part
way in a random order and the die at the first sign of trouble.
-----Original Message-----
*From:* [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf
Of *Grignon Mickaël
*Sent:* Friday, June 23, 2006 11:02 AM
*To:* rsync
*Subject:* rsync and mysql with users connected
Hi,
I want to apologise for my bad english (I'm french).
So I need to Back-up a lot of datas from a place to an another by
the way of rsync with ssh naturally.
A good question from my boss was :
What happened when the mysql database is used by a user during the
Backup ?
Is the system stop the Backup or is it transparency for rsync ?
Sorry if my question is stupid but I haven't already finish the
reading of all the documents treating rsync.
Thanks in advance to your answers and comprehension.
Oh yes, I forgot an important fact : The Backup is done between SUSE
10.0 and Mandrake 10.0 so Linux envirronement. Some datas froms
Windows will be Backuped too. I think we will use a ntfs partition.
Some advises about that or all is OK and though that don't cause any
problems ?
Mickaël.
I see no one has considered dumping to a file and backing up that...
We do that here because we use innodb heavily. We dump using the
extended insert option (see the mysql manual for more info) then rsync
this file. We first sort the records, dump then rsync. Has been working
well for years.
--
Thanks,
James
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