| Showing entries 1 to 13 |
While doing some routine fiddling regarding some topic I've now forgotten, I discovered that ndb_restore was doing something quite surprising. It's been common wisdom for some time that one can use ndb_restore -m to restore metadata into a new cluster and automatically have your data re-partitioned across the data nodes in the destination cluster. In fact, this was the recommended procedure for adding nodes to a cluster before online add node came along. Since MySQL Cluster 7.0, though, ndb_restore hasn't behaved that way, though that change in behavior doesn't seem to be documented and most don't know that the change ever took place.
I'll go through some of the methods you can use to find information about the partitioning strategy for an NDB table, talk a bit about why ndb_restore stopped working the way most everyone expected
Yesterday I was discussing with a fellow DBA about ways to check the status of existing and/or past RMAN jobs. Good backup scripts usually write their output to some sort of log file so, checking the output is usually a straight-forward task. However, backup jobs can be scheduled in many different ways (crontab, Grid Control, Scheduled Tasks, etc) and finding the log file may be tricky if you don’t know the environment well.
Furthermore, log files may also have already been overwritten by the next backup or simply just deleted. An alternative way of accessing that information, thus, may come handy.
Fortunately, RMAN keeps the backup metadata around for some time and it can be accessed through the database’s V$ views. Obviously, if you need this information because your database just crashed and needs to be restored, the method described here is useless.
[Read more...]USE `schema`;
Applying binary logs to a MySQL instance is not particularly difficult, using the mysqlbinlog command line utility:
$> mysqlbinlog mysql-bin.000003 > 03.sql $> mysql < 03.sql
Turning off binary logging for a session is not difficult, from the MySQL commandline, if you authenticate as a user with the SUPER privilege:
mysql> SET SESSION sql_log_bin=0;
However, sometimes you want to apply binary logs to a MySQL instance, without having those changes applied to the binary logs themselves. One option is to restart the server binary logging disabled, and after the load is finished, restart the server with binary logging re-enabled. This is not always possible nor desirable, so there’s a better way, that works in at least versions 4.1 and up:
The mysqlbinlog utility
rsnapshot is a filesystem snapshot utility for making backups of local and remote systems, based on rsync. Rather than just doing a complete copy every time, it uses hardlinks to create incrementals (which are from a local perspective a full backup also). You can specify how long to keep old backups, and all the other usual jazz. You’d generally have it connect over ssh. You’ll want/need to run it on a filesystem that supports hardlinks, so that precludes NTFS.
In the context of MySQL, you can’t just do a filesystem copy of your MySQL data/logs, that would be inconsistent and broken. (amazingly, I still see people insisting/arguing on this – but heck it’s your business/data to gamble with, right?)
Anyway, if you do a local mysqldump also, or
[Read more...]Since writing and speaking a bit more about the “relax! a failure is not an emergency” concept, more and more people approach me with interesting horror stories. I’m scribbling a few backup-related ones here for your enjoyment - and naturally there are important lessons.
[Read more...]Story 1: A place makes backups that get shipped off-site, interstate even. One day a couple of files are lost, and so someone files a request to retrieve said files from the archive. Well, apparently that’s something that should be done as it creates some very stressed responses and a quoted timeline of a few weeks. In the end the issue is resolved through other means and the request stopped - unfortunate, since it would have been very interesting if the requested files would actually ever arrive… clearly a retrieval was not part of the expected process. One also wonders how
Sure, you've heard it before: [some company's logo] has a new MySQL backup tool that promises to solve all of your data recovery needs. The good news is most of these tools work pretty well. However, they tend to suffer from a similar set of limitations. Most require sophisticated infrastructures or complex setup and maintenance and can become a resource drain for some organizations. You're probably wondering, "Why can't someone build a fully automated MySQL backup solution that you can just turn on and forget?"
I am happy to say that the MySQL Developers at Sun are doing just that. In fact, a prototype will be demonstrated at the 2009 MySQL Users' Conference that will show the feasibility of a fully automated MySQL backup and recovery tool. It's being called the MySQL Time Machine and (with all due respect to all vendors with products of similar names) it allows you to
[Read more...]Sure, you've heard it before: [some company's logo] has a new MySQL backup tool that promises to solve all of your data recovery needs. The good news is most of these tools work pretty well. However, they tend to suffer from a similar set of limitations. Most require sophisticated infrastructures or complex setup and maintenance and can become a resource drain for some organizations. You're probably wondering, "Why can't someone build a fully automated MySQL backup solution that you can just turn on and forget?"
I am happy to say that the MySQL Developers at Sun are doing just that. In fact, a prototype will be demonstrated at the 2009 MySQL Users' Conference that will show the feasibility of a fully automated MySQL backup and recovery tool. It's being called the MySQL Time Machine and (with all due respect to all vendors with products of similar names) it allows you to
[Read more...]Sure, you've heard it before: [some company's logo] has a new MySQL backup tool that promises to solve all of your data recovery needs. The good news is most of these tools work pretty well. However, they tend to suffer from a similar set of limitations. Most require sophisticated infrastructures or complex setup and maintenance and can become a resource drain for some organizations. You're probably wondering, "Why can't someone build a fully automated MySQL backup solution that you can just turn on and forget?"
I am happy to say that the MySQL Developers at Sun are doing just that. In fact, a prototype will be demonstrated at the 2009 MySQL Users' Conference that will show the feasibility of a fully automated MySQL backup and recovery tool. It's being called the MySQL Time Machine and (with all due respect to all vendors with products of similar names) it allows you to
[Read more...]The Maatkit toolkit is a real blessing for the MySQL DBA. And while its documentation is pretty good, in some cases it’s necessary to read carefully a second and third time to make sure you are not missing an important piece of information. In this article I will comment on mk-table-chksum and mk-table-sync. My comments are mostly aimed at those DBAs who are considering using these utilities with medium or larger-sized databases.
This option allows you to store the checksum results on the master, in a table that will get replicated to the slaves. Although it might seem like overhead for a simple check, it really simplifies your life, especially when used
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