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PowerDNS OpenDBX Backend - Installation

From Wiki

Contents

• 1 Installation
       1.1 Compilation
       1.2 Configuration options
       1.3 Backend specific configuration
          ☆ 1.3.1 MySQL
          ☆ 1.3.2 PostgreSQL
          ☆ 1.3.3 SQLite and SQLite3
          ☆ 1.3.4 MS SQL Server
          ☆ 1.3.5 Sybase ASE
       1.4 Database setup
       1.5 Migration

Installation

Compilation

Before performing the steps to compile the PowerDNS server and the OpenDBX
backend you have to install the OpenDBX library, the OpenDBX backend you want
to use and its development package, which includes the necessary header. The
OpenDBX package can be downloaded from Linuxnetworks.de.

Apply these steps to the source pdns-x.xx.tar.gz file, if you don't want to use
a precompiled package:

* Extract the pdns tar file
* Change into the newly created pdns directory
* Extract the opendbxbackend tar file
* Run "cat <patch> | patch -p1" (if available)
* Type ./configure --help for the available options
* For dynamic modules:
  ./configure
     --prefix=/usr
     --with-modules=""
     --with-dynmodules="opendbx"
     --enable-recursor
* For a static module:
  ./configure
     --prefix=/usr
     --with-modules="opendbx"
     --with-dynmodules=""
     --enable-recursor
* make && make install

Configuration options

There are a few options through the OpenDBX backend can be configured for your
environment. Add them to the pdns.conf file located in /etc/powerdns or /usr/
local/etc/ (depends on your configuration while compiling):

opendbx-backend (default "mysql") 
    Name of the backend used to connect to the database server. Currently
    mysql, pgsql, sqlite, sqlite3 and sybase are available.

opendbx-host-read (default "127.0.0.1") 
    One or more host names or IP addresses of the database servers. These hosts
    will be used for retrieving the records via SELECT queries.

opendbx-host-write (default "127.0.0.1") 
    Same as opendbx-host-read, except for INSERT/UPDATE statements (mostly used
    by zonetransfers).

opendbx-port (default "") 
    TCP/IP port number where the database server is listening to. Most
    databases will use their default port if you leave this empty.

opendbx-database (default "powerdns") 
    The database name where all domain and record entries are stored.

opendbx-username (default "powerdns") 
    Name of the user send to the DBMS for authentication.

opendbx-password (default "") 
    Clear text password for authentication in combination with the username.

opendbx-host (deprecated, default "127.0.0.1") 
    Host name or IP address of the database server. This parameter is
    deprecated in favor of opendbx-host-read and opendbx-host-write.

Backend specific configuration

MySQL

Supported without changes since OpenDBX 1.0.0

PostgreSQL

Supported without changes since OpenDBX 1.0.0

SQLite and SQLite3

Supported without changes since OpenDBX 1.0.0 but requires to set opendbx-host
to the path of the SQLite file (including the trailing slash or backslash,
depending on your operating system) and opendbx-database to the name of the
file, e.g.

opendbx-host-read = /path/to/file/
opendbx-host-write = /path/to/file/
opendbx-database = powerdns.sqlite

MS SQL Server

Supported by PowerDNS 2.9.20 (with latest patch) and OpenDBX 1.1.4 by using the
FreeTDS library. It uses a different scheme for host configuration (requires
the name of the host section in the configuration file of the dblib client
library) and doesn't support the default statement for starting transactions.
Please add the following lines to your pdns.conf:

opendbx-host-read = MSSQL2k
opendbx-host-write = MSSQL2k
opendbx-sql-transactbegin = BEGIN TRANSACTION

Sybase ASE

Supported by PowerDNS 2.9.20 (with latest patch) and OpenDBX 1.1.5 by using the
native Sybase ctlib or the FreeTDS library. It uses a different scheme for host
configuration (requires the name of the host section in the configuration file
of the ctlib client library) and doesn't support the default statement for
starting transactions. Please add the following lines to your pdns.conf:

opendbx-host-read = SYBASE
opendbx-host-write = SYBASE
opendbx-sql-transactbegin = BEGIN TRANSACTION

Database setup

You need one of the DBMS supported by the OpenDBX library for storing your
records and domain infomation. Please have a look at the documentation of your
DBMS for the task of creating a database and an user.

After that you're almost done. Use the appropriate table definition below to
create the tables in the new database after which you can populate your
database with dns information with e.g. zone2sql.

• MySQL
  • PostgreSQL
  • SQLite
  • Sybase

Migration

To convert an existing gMySQL Database to an OpenDBX MySQL database, an
additional status column is required since patch 2.9.20-3:

ALTER TABLE domains ADD ( status CHAR(1) NOT NULL DEFAULT 'A' )

Adding a foreign key constraint from records.domain_id to domains.id is a good
idea too:

ALTER TABLE records ADD CONSTRAINT fk_records_domainid
FOREIGN KEY (domain_id) REFERENCES domains (id)
ON UPDATE CASCADE ON DELETE CASCADE

You should also recreate your indices for optimal performance. Please have a
look in the appropriate file listed in the section above.

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PowerDNS OpenDBX Backend - Optimization

From Wiki

Contents

• 1 Optimization
       1.1 Use NULL for prio and ttl fields

Optimization

Use NULL for prio and ttl fields

Each DNS entry in the record table has its own values for time-to-live (TTL)
and priority. You can speed up processing of each query in the OpenDBX backend
if you set both values in your records table to NULL by default and only set
them to an appropriate value if you really need them.

There are two record types where you can't use NULL in the prio fields: MX and
SRV record types. Most of the time you need different values than 0 (which NULL
is converted to in the OpenDBX backend) in those records but everywhere else
NULL is suggested.

The same applies to the TTL field in each record. There are only a few cases
where you might wish to use different values than the default one you can set
by the default-ttl=... config option in the pdns.conf file.

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PowerDNS OpenDBX Backend - Comparison

From Wiki

Contents

• 1 Comparison
       1.1 Environment
       1.2 Settings
       1.3 Test description
       1.4 Results
       1.5 Conclusion
       1.6 Optimizations

Comparison

Environment

The test environment consisted of two different machines both running Debian
3.1 (Sarge) with the latest official patches applied. The following packages
were used:

PowerDNS 
    Version 2.9.18-svn (rev 474, 2005-09-03)
PowerDNS OpenDBX Backend 
    Version from 2005-10-15 (source)
OpenDBX 
    Version 0.9.5 (more)
MySQL 
    Version 4.1.11a, including libmysqlclient14
PostgreSQL 
    Version 7.4.7
SQLite3 
    Version 3.2.1

One hosted the PowerDNS server while the other was responsible for running the
test suite (queryperf is included in the BIND sources):

PowerDNS + database server 
    VIA C3 533MHz, 256MB RAM
Benchmark client 
    Pentium M 1.5GHz, 512MB RAM

Both machines were connected by a 100MBit network and they were the only ones
attached to the hub.

Settings

All test were done with default settings for each database - no further
optimizations were applied except if stated otherwise.

To get raw database and backend performance, caching in PowerDNS was switched
of generally. Otherwise we would get much higher but false results due to
packet caching done by PowerDNS. The "slave-cycle-interval" parameter was set
to a value high enough so checking for unfresh slaves had no negative
influence:

• cache-ttl=0
  • negquery-cache-ttl=0
  • query-cache-ttl=0
  • recursive-cache-ttl=0
  • master=yes
  • slave-cycle-interval=300

Test description

The test was based on the records in the example.com zone available in the
regression-tests directory of PowerDNS. The zone file was converted by zone2sql
(part of the PowerDNS distribution) to a set of SQL queries inserted into the
database tables created by specific "create table" statements for each DBMS
(available along with the OpenDBX backend sources).

Lookup speed 
    This was tested by running queryperf with a query set of 10000 A records
    (host-0.example.com to host-9999.example.com) three times in a row.
    Afterwards these results were averaged to be a good rule of thumb for real
    live environments (cache hit rate of 60 to 70 percent).

AXFR speed 
    Zone transfer measurement was done by running "host -l example.com
    <serverip> 1>/dev/null" 100 times in a loop while timing the test. Possible
    variation of the results due to the operating system should be minimal.

Results

Values for queryperf results are the averaged number of queries per second
determined by queryperf.

Backend    gmysql OpenDBX OpenDBX OpenDBX
                     mysql   pgsql  sqlite3
1. queryperf 446    454     270     839
2. queryperf 1033   1118    272     848
3. queryperf 1033   1118    272     844
Lookup (avg) 837    897     271     844
 AXFR (sec)  198    160     271     224

Conclusion

• The OpenDBX backend outperforms the native MySQL backend by ca. 7 percent
    in lookups
  • OpenDBX backend zone transfers are even 20 percent faster than gmysql
    backend
  • A PostgreSQL server needs optimized settings before it can perform well
  • SQLite is a good alternative for systems without dedicated server

Optimizations

I would like to know which settings are needed to get comparable performance
figures for PostgreSQL. If you have any suggestions please add them to the Talk
page.