A live recording of my LinuxTag 2010 presentation entitled Storage Done Right: Building a Resilient, Distributed, Highly Available Open Source iSCSI SAN is now available from our web site. If you want to find out how to build a complete SAN from 100% open source, do take a look!

I do apologize for the less-than-optimal sound quality. I did the recording myself with my laptop mike, so unfortunately there’s quite a bit of clipping in the audio track. I hope my ramblings are still somewhat audible.

…

Mikeal Rogers wrote a blog post on MongoDB performance and durability. In one of the sections, he writes about the request/response model, and makes the following statement:

MongoDB, by default, doesn’t actually have a response for writes.

In response, one of 10gen employees (the company behind MongoDB) made the following comment on Hacker News:

We did this to make MongoDB look good in stupid benchmarks.

The benchmark in question shows a single graph, which demonstrates that MongoDB is 27 times faster than CouchDB on inserting one million rows. At the first glance, the benchmark immediately looks silly if you've ever done serious benchmarking before. CouchDB people are smart, inserting …

I was configuring MySQL Cluster where the application servers use a properties file to connect to the MySQL Data/Storage node (I configured both Data and Storage nodes on same physical server).
I want the application to use a single IP address, to access the DB servers in cluster. Since if any of the nodes fail, the application servers should still be able to query the databases.
Hence I thought of using LVS so that multiple application servers can access the DB servers through VIP. To achieve the same I have configured LVS, thought of sharing the same.

RHEL Linux LVS setup:
=====================

Pre-Requisites:
===============

REDHAT Linux Cluster Packages
VIRTUAL IP

Configuration for LB server:
============================

Configure packet forwarding on LB server

vi /etc/sysctl.conf

net.ipv4.ip_forward = 1       …

I was configuring MySQL Cluster where the application servers use a properties file to connect to the MySQL Data/Storage node (I configured both Data and Storage nodes on same physical server).
I want the application to use a single IP address, to access the DB servers in cluster. Since if any of the nodes fail, the application servers should still be able to query the databases.
Hence I thought of using LVS so that multiple application servers can access the DB servers through VIP. To achieve the same I have configured LVS, thought of sharing the same.

RHEL Linux LVS setup:
=====================

Pre-Requisites:
===============

REDHAT Linux Cluster Packages
VIRTUAL IP

Configuration for LB server:
============================

Configure packet forwarding on LB server

vi /etc/sysctl.conf

net.ipv4.ip_forward = 1       …

Mikeal Rogers wrote a blog post on MongoDB performance and durability. In one of the sections, he writes about the request/response model, and makes the following statement:

MongoDB, by default, doesn’t actually have a response for writes.

In response, one of 10gen employees (the company behind MongoDB) made the following comment on Hacker News:

We did this to make MongoDB look good in stupid benchmarks.

The benchmark in question shows a single graph, which demonstrates that MongoDB is 27 times faster than CouchDB on inserting one million rows. At the first glance, the benchmark immediately looks silly if you’ve ever done serious benchmarking before. CouchDB people are smart, inserting …

Some of you may have noticed that blob streaming has been merged into the main Drizzle tree recently. There are a few hooks inside the Drizzle kernel that PBMS uses, and everything else is just in the plug in.

For those not familiar with PBMS it does two things: provide a place (not in the table) for BLOBs to be stored (locally on disk or even out to S3) and provide a HTTP interface to get and store BLOBs.

This means you can do really neat things such as have your BLOBs replicated, consistent and all those nice databasey things as well as easily access them in a scalable way (everybody knows how to cache HTTP).

This is a great addition to the AlsoSQL arsenal of Drizzle. I’m looking forward to it advancing and being adopted (now much easier that it’s in the main repository)

• …

Connector/J provides a useful load-balancing implementation for Cluster or multi-master deployments.  As of Connector/J 5.1.12, this same implementation is used under the hood for balancing load between read-only slaves with ReplicationDriver.  When trying to balance workload between multiple servers, though, the driver has to decide when it’s safe to swap servers – doing so in the middle of a transaction would not make applications very happy.  Many of the same principles which apply to autoReconnect also apply here – you don’t want to lose important state information.

As a result, Connector/J will only try to pick a new server when one of the following happen:

1. At transaction boundaries (transactions are explicitly committed or rolled back)
2. A communication …

Ronald saved me a post by giving his feedback on a few Oracle conferences that now have MySQL content.

My opinion is pretty much a summary of Ronald’s post, so I won’t repeat it here. Instead, I’ll post about a conference he did not, the 4th Extremely Large Databases Conference. I am particularly interested in any MySQL folks planning to attend (I would expect Tokutek to be represented, and maybe even the Calpont folks).

Most of this is directly from an e-mail I received from Jacek Becla, who had a keynote at the 2008 MySQL User Conference and Expo. If you also received this e-mail, please feel free to skip …

When working interactively with the MySQL client, you receive feedback of the time the query took to complete to a granularity of 10 ms.

Enabling profiling is a simple way to get more a more accurate timing of running queries. In the following example you can see the time the kernel took to run an explain, the query, and alter, and repeat explain and query.

mysql> set profiling=1;
mysql> EXPLAIN SELECT ...
mysql> SELECT ...
mysql> ALTER ...
mysql> show profiles;
+----------+------------+-------------------------
| Query_ID | Duration   | Query
+----------+------------+-------------------------
|        1 | 0.00036500 | EXPLAIN SELECT sbvi.id a
|        2 | 0.00432700 | SELECT sbvi.id as sbvi_i
|        3 | 2.83206100 | alter table sbvi drop in
|        4 | 0.00047500 | explain SELECT sbvi.id a
|        5 | 0.00367100 | SELECT sbvi.id as sbvi_i
+----------+------------+-------------------------

More information at …

Your searching for how to create a join across two databases on two different servers and it can’t be done directly.   select  d1.a, d2.b from db1@server1 join db2@server2 where db1.c = db2.c; does not work.

You learn about federated databases.  The federated storage engine allows accesses data in tables of remote databases.  Now how do you make it work?

1) Check if the federated storage engine is supported.  Federation is OFF by default!

mysql> show engines;
+------------+---------+----------------------------------------------------------------+
| Engine     | Support | Comment                                                        |
+------------+---------+----------------------------------------------------------------+
| InnoDB     | YES     | Supports transactions, row-level locking, and foreign keys     |
| MyISAM     | DEFAULT | Default engine as of …