The full Linux cluster stack, including Pacemaker, Heartbeat, Corosync and related packages, cleared all hurdles and migrated to the Debian testing repository this morning. This means that Pacemaker and both messaging layers it supports will be in the upcoming Debian release, codenamed squeeze.
Credit goes to the debian-ha maintainers crowd for making this possible: Martin Loschwitz, …
[Read more]In the last few months we’ve got couple of bugs with the PBXT read/write locking code. One of the problems was directly in the lock/grant algorithm. It was strange to find such kind of error after quite long time of various testing and real-life usage. From the point of view of QA it was clear that manual code review was not efficient in this case.
Given all this I decided to try formal verification of the code. The specifics of the PBXT locking code is that it’s relatively small (about 100 LOC) but quite complex. The algorithm itself is not that trivial but the major source of complexity is concurrent execution of its parts. So if I had to manually create a finite state table for it then it would be essentially a cartesian product of states of all concurrent threads. In numbers that is if there is about 20-30 states per thread and there are 3 threads (empirically I estimated that threads beyond 3 don’t add more states) then I would …
[Read more]A special extended edition of Tech Messages for 2010-04-29 through 2010-05-14:
Upgrading from MySQL 5.0 to MySQL 5.1 or Percona Server 5.1 you may run into issues with mysql_upgrade - it will identify some tables to be upgraded and will attempt to run REPAIR TABLE for them. This will fail with "The storage engine for the table doesn't support repair" error message. This seems to confuse a lot of people and I've seen people doing failsafe upgrade path of dumping and reloading complete database confused by this error message, which of course works, but can take quite a lot of time.
Another solution is to simply run ALTER TABLE tbl
ENGINE=INNODB which will rebuild table with new MySQL
version and normally will fix issues identified by
mysql_upgrade.
You can use mysqlcheck -A --check-upgrade to
identify tables which need to be fixed such a way.
With Oracle intentions to make Innodb default storage engine in next MySQL release I'm hopeful minor annoyances …
[Read more]These days I spend more time looking at /proc/diskstats than I do at iostat. The problem with iostat is that it lumps reads and writes together, and I want to see them separately. That’s really important on a database server (e.g. MySQL performance analysis).
It’s not easy to read /proc/diskstats by looking at them, though. So I usually do the following to get a nice readable table:
Here’s a recipe. You might want to refer to the kernel iostat documentation too.
wget http://aspersa.googlecode.com/svn/trunk/rel
wget http://aspersa.googlecode.com/svn/trunk/align
chmod +x rel align
while sleep 1; do grep sdb1 …
We were discussing the recommendations we issue each quarter
around MySQL and the question of using InnoDB plugin came up. We
usually follow Planet MySQL closely, so we read what the blogs
had to say and it was all good, but we decided to provide our
users some data of our own. We used our own sysbench
tests on to get the information we needed.
A Word About BenchmarksI don't trust most of the benchmarks that
are published online because they really apply to the use case of
whomever is writing the article. They are usually many factors
that can influence them and I find it difficult to apply them
as-is to our environment.
I do trust the benchmarks published online as a reference on how
to create and run our own benchmarks. So this article is based on
this premise. I recommend you to do your own homework to …
As everyone knows, I am a command line guy. I am very much
comfortable with the shell prompt and the command line SQL
client. I do most of my work that way, and I am very much
productive.
However, there comes a time when even for a command line
enthusiast a GUI can be helpful.
Here comes the latest MySQL Workbench 5.2.
There are two areas where I feel that WB can give me a
hand:
The first is when looking at tables that contain BLOB columns.
Sure I can deal with them at the command line, but this editor
makes my life easier.
When a column contains a BLOB, you can open the field
viewer.
…
Welcome to Log Buffer, a weekly review of the database industry. This week’s issue Log Buffer #189 is generously published by Iggy Fernandez, editor of the quarterly journal of the Northern California Oracle User Group (NoCOUG).
As always, if you’d like to host your own issue of Log Buffer, simply reach out to the Log Buffer coordinator.
Please enjoy Iggy’s issue of …
[Read more]
I dislike the old perfmon interface and it's unreadable graphs
and logs. For a long time I've been searching for a basic
vmstat and/or iostat
windows port, and one that doesn't rely on that nonsensical
cygwin. If anybody knows of one, please leave a comment.
Here's a proof on concept I cooked up in 20 minutes using the
PDH (performance data helper) functions. In a
nutshell, it queries the PDH counters directly and I'm be free to
displaythe data however I like.
Here's what I got so far:
[Read more]
proc_q_len pagefile interrupt/s cswitch/s %cpu_user %cpu_sys %cpu_idle %disk_busy %disk_read %disk_write
10 …
Sometimes we may need to collect facebook user’s basic data for our website or application. Then we’ve to call graph api or legacy api or fql query to collect some specific data. This is a basic requirements for most of the fbconnect base website or facebook application. To simplify this task here I published some code so that you could easily use this code and can integrate in your site. Read Full Article
