[SOLVED] Moving to a new machine

yoachan · 10-06-2010, 11:46 AM

Dear all,

We are planning to move our site to a new machine, with as little as down time as possible. The site is a small forum, so it can always changing every minutes.
As a note both machine are remote machine. We only have ssh tunnel and http connection.
So here is what we have for a plan:

Copy all data (and database) from old machine to the new machine using rsync
Make an announcement that at scheduled time, there will be a down time.
Reduce TTL for DNS (www.mysite.com)
Make a dummy name for testing (dummy.mysite.com)
make dummy.mysite.com as a mirror copy (at certain point) of www.mysite.com
At scheduled time, make both www.mysite.com and dummy.mysite.com offline, and point DNS www.mysite.com to new machine, pointing the same directory as dummy.mysite.com, and remove name for dummy.mysite.com
re-rsync databases on both machine
After rsync completed, turn www.mysite.com on new machine online

My question is:

Will this plan works?
Can rsync copy changed part of a file instead of copying whole file? Assuming mysql MYD file changed because of mysql transaction, can rsync copy only part of file that changed instead of copying whole file again? Copying over 100+ MB mysql file only because of mysql add a single record won't be a smart move...
Does anyone have a better and easier plan to do this?

This is my first experience moving host on a live site.
Any help appreciated.

Thanks and regards,

yoachan

mago · 10-06-2010, 01:20 PM

yes rsync will sync up the changes once the bulk has been copied over.

man rsync will show you all you need.

yoachan · 10-06-2010, 09:05 PM

@Mago: Thanks, Man! This bring me a relief

Blue_Ice · 10-07-2010, 01:17 AM

I wouldn't use rsync on the databases. I would do a backup and restore or set up mysql replication. rsync'ing databases can cause problems with the integrity of the database.

quanta · 10-07-2010, 02:32 AM

Agree with Blue Ice. I would like to suggest you use mysqldump.

yoachan · 10-09-2010, 08:56 PM

The problem is dumped database will takes time to be copied over.
For this two machines were thousands mile away. One in US and one in Asia.

Any other solution(s)?

mago · 10-09-2010, 09:06 PM

How big is the dump?.
How much does it weight compress?.
How long is the maintenance window?

Which engine are you using for MySQL?

There are lots of ways to skin a cat, one just need some info.

yoachan · 10-09-2010, 09:29 PM

The biggest chunk is 550MB, and will take transfer time 30-60 minutes.
Other databases are smaller. To move everything will takes approximately two hours...
I didn't do compression, but I'm using on the fly compression during rsync/scp.

Just thinking that direct rsync will be easier, faster, and fail-proof

We just want our down time as short as it can, just for user's comfort

mago · 10-09-2010, 09:39 PM

Well if you use InnoDB and you can enable binary logs, upload the dump of the day before and sync up the logs of the day, then import from the logs up to the date.

Another way to go is to compress on the fly the same day:

Code:

mysqldump --opt --single-transaction -uuser -ppassword database | gzip -9 | ssh user@remoteserver "dd of=/path/for/dump/backup-`date +%Y%m%d`.sql.gz"

Or you can dump all databases at once, compress and transfer them with the same method, usually the compression rate is 8/9 to 1.

So if 550MB is the largest this way you transfer about 60MB then uncompress on destination server and import it.

Let me know how it goes.

yoachan · 10-10-2010, 10:23 PM

Tomorrow will be the D-Day
Today we prepare everything that needed.

yoachan · 10-15-2010, 05:04 AM

Huff... huff...
All data moved.
rsync home directories and document_roots,
dump and zip databases than transfers.

Still waiting for DNS to propagate.

Thanks for everyone's help