linuxsutra

   Chapter 1. SVN What?
   Chapter 2. SVN Why?
   Chapter 3. SVN How?
   Chapter 4. SVN Stack
   Chapter 5. SVN Install Instructions
          5.1  Apache for SVN
          5.2  Subversion
          5.3  Subversion authentication & authorization
          5.4  cvs2svn
          5.5  SVNSYNC
          5.6  REVERSE SYNC
          5.7  SYNC AUTOMATE
          5.8  WRITE THRU PROXY
   Chapter 6. Errors & Resolutions
   Chapter 7. WebSVN
   Chapter 8. gonzui

SVN Install Instructions | Apache for SVN:

       Now,
               mkdir /home/myname/svn-install-scripts
               cd /home/myname/svn-install-scripts/
               wget http://mirrors.24-7-solutions.net/pub/apache/httpd/httpd-2.2.6.tar.gz
        gunzip httpd-2.2.6.tar.gz
        tar xvf httpd-2.2.6.tar
        cd httpd-2.2.6
       If 32 bit arch use "-m32" in CFLAGS, elseif 64 bit arch use "-m64 -fPIC" in arch.
               CFLAGS="-m32"
                ./configure
        --prefix=/home/myname/svn/softwares/apache-2.2.6
        --enable-rewrite=shared
        --with-z=/usr
        --enable-cgi=shared
        --enable-info=shared
        --enable-ssl=shared
        --enable-so
        --enable-ext-filter=shared
        --enable-log-forensic=shared
        --enable-mime-magic=shared
        --enable-expires=shared
        --enable-usertrack=shared
        --enable-headers=shared
        --enable-unique-id=shared
        --enable-dav=shared
        --enable-dav-fs=shared
        --enable-vhost-alias=shared
        --with-mpm=prefork
        --enable-nonportable-atomics=yes
               make
               make install
       Edit /home/myname/svn/softwares/apache-2.2.6/conf/httpd.conf
               Listen 80
               #OR SOME CUSTOM PORT
               #Selinux should be permissive or disabled if you require to run in any port less than 1000

       POST INSTALL CONFIGURATION AND LSB SCRIPTS:
       Only if ipaddress, hostname is found missing in /etc/hosts.. add it.
               Eg:
                       echo "MySubversionIndiaServer         MySubversionIndiaServer.mylab.com         MySubversionIndiaServer" >> /etc/hosts
       Create & Edit /etc/rc.d/init.d/httpd-svn
               #SET APPROPRIATE PATHS - REPLACE APACHE HOME BY THE PREFIX SUPPILED DURING APACHE INSTALL
       chmod 0755 /etc/rc.d/init.d/httpd-svn
       chkconfig --add httpd-svn
       chkconfig --level 2345 httpd-svn on
       /etc/rc.d/init.d/httpd-svn start

SELinux when enforced can make a lot of things not work. Features developed at
an server(SELinux disabled) may not work when it goes to production. SELinux controls
httpd (Apache) and I can list down few pointers for you.
Errors:

1. You see errors when you try creating a VirtualHost having its DocumentRoot on directories other than /var/www/html
2. You see errors when you try starting apache on non standard ports other than ones listed below
                           http_cache_port_t              tcp      3128, 8080, 8118
                           http_cache_port_t              udp      3130
                           http_port_t                        tcp      80, 443, 488, 8008, 8009, 8443
                           pegasus_http_port_t            tcp      5988
                           pegasus_https_port_t           tcp      5989
3. Your script does not execute if you are trying to run system files in it.
   Eg:
   You are trying to run /usr/bin/crontab, etc from php.

So.. what are we supposed to do? There are two possibilities.

• Disable selinux (refer SELINUX Restrictions On Apache). But kindly dont since it is not required.
• Or set SElinux to allow what you wan't
  

SELinux can be configured by setting selinux booleans and also by changing the context of the scripts. So.. what is this context? You will come to know below.

        cat /var/log/messages | grep SELinux

and later accordingly, allow selinux to relax restrictions on httpd.

Manual:
        man 8 httpd_selinux

Is SELinux enabled?
        dmesg | grep selinux
        cat /selinux/enforce

To see processes protected by selinux:
                ps -ZC httpd

For entire list
                ps -eZ

File attributes
                ls -Z /usr/bin/crontab
                       -rwxr-xr-x  root     root     system_u:object_r:bin_t          /usr/bin/crontab                Selinux prevents:
                        ls -Z /home/praveen/info.php
                        -rw-rw-r--  praveen  praveen  user_u:object_r:user_home_t     /home/praveen/test.php
                Selinux allows:
                        ls -Z /home/praveen/info.php
                                -rw-rw-r--  praveen  praveen  user_u:object_r:httpd_sys_content_t      /home/praveen/test.php

Types avaliable for apache
                getsebool -a | grep httpd

allow_httpd_anon_write --> off
allow_httpd_bugzilla_script_anon_write --> off
allow_httpd_mod_auth_pam --> off
allow_httpd_nagios_script_anon_write --> off
allow_httpd_squid_script_anon_write --> off
allow_httpd_sys_script_anon_write --> off
httpd_builtin_scripting --> on
httpd_can_network_connect --> off
httpd_can_network_connect_db --> off
httpd_can_network_relay --> off
httpd_disable_trans --> off
httpd_enable_cgi --> on
httpd_enable_ftp_server --> off
httpd_enable_homedirs --> on
httpd_rotatelogs_disable_trans --> off
httpd_ssi_exec --> off
httpd_suexec_disable_trans --> off
httpd_tty_comm --> off
httpd_unified --> on

Sometimes restorecon -v test.php can work.

Recursively,
         restorecon -Rv <dir>

The below command will allow apache to access your directory(non default)
chcon -Rt httpd_sys_content_t <your document root dir>

The command below will allow apache to access user home directories as document root:
setsebool -P httpd_enable_homedirs=1

To use system commands thru php or other scripts on apache.. that command's context should be changed to httpd_unconfined_script_exec_t.
Eg:
chcon -t httpd_unconfined_script_exec_t /usr/bin/crontab

For other, undiscussed policy related errors:
        tail -f /var/log/messages | grep SELinux
        sealert -l <id>
will tell you what to do.

Last option will be to disable SELinux protection to apache by:
       setsebool -P httpd_disable_trans 1
       /etc/init.d/httpd restart

So disabling SELinux is not the solution if you have Apache issues.

If you want to control the maximum upload file size limit in php don't try doing it
thru script like:
  ini_set('UPLOAD_MAX_FILESIZE', <value>);
  ini_set('POST_MAX_SIZE', <value>);
Instead set the values in php.ini like:
  upload_max_filesize = 256M ;(it is 2M by default)
  post_max_size = 256M
Do a httpd graceful. It should work.

        default=0
        timeout=5
        splashimage=(hd0,0)/boot/grub/splash.xpm.gz
        hiddenmenu
        title CentOS (2.6.9-55.0.6.plus.c4smp)

#LABEL=/home             /home                   ext3    defaults        1 2

LABEL=/home             /home                   reiserfs    defaults        1 2

Common errors, its context and its resolution(fix,dirtyfix):

Error:
rsync: recv_generator: mkdir "" failed: Too many links (31)
rsync: stat "" failed: No such file or directory (2)
rsync: mkstemp ".MXiMwF" failed: No such file or directory (2)
Resolution:
Go for reiserfs or gfs or comply with ext3 subdirectories limitation

---

Context:
svnsync (reversal)
Error:
svnsync: PROPFIND of '/mysvn': Could not resolve hostname `myhost'
Resolution:
ip instead of hostname

---

Context:
svn-python
>>>import svn.repos
Error:
undefined symbol: gss_delete_sec_context
Resolution:
Edit Makefile
#SVN_APR_LIBS =  path-to-apache-x.x.x/lib/libapr-x.la -luuid -lrt -lcrypt  -lpthread -ldl
SVN_APR_LIBS =  path-to-apache-x.x.x/lib/libapr-1.la -luuid -lrt -lcrypt  -lpthread -ldl -lgssapi
ln -s /usr/lib/libgssapi.so.x.x.x /usr/lib/libgssapi.so
And make again.

---

Context:
svnsync (reversal)
Error:
svnsync: PROPFIND of '/mysvn': Could not resolve hostname `myhost'
Resolution:
ip instead of hostname

---

Context:
MIME-tools: /usr/bin/perl -MCPAN -e 'install MIME::Parser'
Error:
No IO::File
Undefined subroutine &Mail::Internet::mailaddress
Resolution:
cpan> install IO::File
cpan> force install MIME::Parser

---

Context:
Chart: /usr/bin/perl -MCPAN -e 'install Chart::Base'
Error:
The module Chart::Base isn't available on CPAN
Resolution:
wget http://search.cpan.org/CPAN/authors/id/C/CH/CHARTGRP/Chart-2.4.1.tar.gz
tar zxvf Chart-2.4.1.tar.gz
cd Chart-2.4.1
perl Makefile.PL
make
make test
make install

---

Error:
Starting httpd: Warning: DocumentRoot [path-to-bugzilla] does not exist
Forbidden
You don't have permission to access /README on this server.
Additionally, a 403 Forbidden error was encountered while trying to use an
ErrorDocument to handle the request.
Resolution:
sestatus
cat /selinux/enforce
echo 0 >/selinux/enforce
newrole -r sysadm_r
cat /selinux/enforce
vi /etc/selinux/config
    SELINUX=disabled
reboot

---

Context:
mysqlhotcopy -u <user> -p <pass> <bd> --debug
Error:
Using copy suffix '_
Filtering tables with '(?-xism:.*)'
Invalid db.table name 'db.table`.`field' at
path-to/mysqlhotcopy line 855.
Dirty fix:
Added a new line
vi path-to/mysqlhotcopy
:836
map { s/^.*?.//o } @dbh_tables;

---

Context:
mysqlhotcopy -u <user> -p <pass> <bd> --debug --addtodest
Error:
DBD::mysql::db do failed: Access denied; you need the RELOAD privilege for
this operation at path-to/mysqlhotcopy line 473.
Resolution:
mysql>
GRANT RELOAD ON *.* TO user@localhost; FLUSH PRIVILEGES;

---

Context:
Can't connect to the database.
Error:
Too many connections
Is your database installed and up and running?
Do you have the correct username and password selected in localconfig?
Resolution:
vi /etc/my.cnf
#max_connections = 100
max_connections = 250
interactive_timeout = 180
wait_timeout = 180
/etc/init.d/mysqld restart

---

Error:
DBD::mysql::db do failed: MySQL server has gone away at mysqlhotcopy line 528.
Resolution:
vi /etc/my.cnf
interactive_timeout = 3600
wait_timeout = 3600
/etc/init.d/mysqld restart

---

Error:
apr-config not found
Resolution:
ln -s path-to/apr-1-config path-to/apr-config

---

Troubleshoot:
tail -f path-to-apache-x.x.x/logs/error_log
Error:
[] () Apache2::SizeLimit httpd process too big, exiting at SIZE=172222/0 KB  SHARE=5222/0 KB  UNSHARED=162222/70000 KB  REQUESTS=2 LIFETIME=0 seconds
Resolution:
Edit mod_perl.pl
        Raise value for$Apache2::SizeLimit::MAX_UNSHARED_SIZE = 70000;

---

Dependency Errors:
missing: fig2dev
*** This tool is provided by docbook-utils ***
*** This tool is provided by sdvel ***
*** This tool is provided by transfig ***
Resolutions:
Load distro CD.
Change dir to CD.
find . | grep "docbook-utils"
rpm -q --provides -p RedHat/RPMS/docbook-utils-0.6.14-4.noarch.rpm
rpm -ivh RedHat/RPMS/docbook-utils-0.6.14-4.noarch.rpm
rpm -ivh RedHat/RPMS/docbook-style-dsssl-1.78-4.noarch.rpm
rpm -ivh RedHat/RPMS/jadetex-3.12-11.noarch.rpm
rpm -ivh RedHat/RPMS/tetex-2.0.2-22.EL4.7.x86_64.rpm
rpm -ivh RedHat/RPMS/tetex-fonts-2.0.2-22.EL4.7.x86_64.rpm
rpm -ivh RedHat/RPMS/tetex-latex-2.0.2-22.EL4.7.x86_64.rpm
rpm -ivh RedHat/RPMS/netpbm-progs-10.25-2.EL4.2.x86_64.rpm
rpm -ivh RedHat/RPMS/netpbm-10.25-2.EL4.2.x86_64.rpm
rpm -ivh RedHat/RPMS/tetex-dvips-2.0.2-22.EL4.7.x86_64.rpm
rpm -ivh RedHat/RPMS/docbook-utils-pdf-0.6.14-4.noarch.rpm
find . | grep "transfig"
rpm -ivh RedHat/RPMS/transfig-3.2.4-8.x86_64.rpm

---

Compile Warning:
missing: cvs2cl devel_product_release
This above warning can be ignored according to:
http://lists.mkgnu.net/pipermail/scmbug-users/2007-February/000786.html
Resolution:
Compile scmbug like ./configure --without-doc

---

Context:
./etc/init.d/scmbug-server start
perl -MCPAN -e 'install Mail::Sendmail';
Error:
make test fails
Resolution:
cpan>
  look Mail::Sendmail
  perl Makefile.PL
  make
  make install

---

Error:
configure: error: Cannot find OpenSSL's
Resolution:
> yum install openssl-devel
Compile optionchanged to --with-openssl instead of --with-openssl=/usr

---

Error:
configure: error: libjpeg.(a|so) not found
Resolution:
> rpm -ivh libjpeg-6b-34.x86_64.rp
> yum install libjpeg-devel
> ln -s /usr/lib64/libjpeg.a /usr/lib/libjpeg.a
> ln -s /usr/lib64/libjpeg.la /usr/lib/libjpeg.la
> ln -s /usr/lib64/libjpeg.so /usr/lib64/libjpeg.so.62.0.0
> ln -s /usr/lib64/libjpeg.so.62 /usr/lib64/libjpeg.so.62.0.0
> ln -s /usr/lib64/libjpeg.so.62.0.0 /usr/lib/libjpeg.so.62.0.0

---

Error:
configure: error: libpng.(a|so) not found
Resolution:
> rpm -ivh libpng-1.2.8-2.x86_64.rpm
> yum install libpng-devel
Create appropriate symlinks from /usr/lib64 to /usr/lib

---

Error:
configure: error: Cannot find pspell
Resolution:
> yum install aspell-devel
Create appropriate symlinks from /usr/lib64 to /usr/lib

---

Cuil.com (pronounced as cool.com) was launched recently.
Much media hype was created regarding the launch.
People searching about cuil on google was really a fun to watch.
They searched for terms like cool, cool.com, kuil, cuil, quil, etc.

http://www.google.com/trends/hottrends?sa=X
http://www.google.com/trends/hottrends?q=cool&date=2008-7-29&sa=X
http://www.google.com/trends/hottrends?q=cuil.com&date=2008-7-29&sa=X
http://www.google.com/trends/hottrends?q=cool.com&date=2008-7-29&sa=X
http://www.google.com/trends/hottrends?q=quil&date=2008-7-29&sa=X
http://www.google.com/trends/hottrends?q=kuil&date=2008-7-29&sa=X

Also, this launch benifits many sides:

first:
Google gets more credibility and hits

second:
Some cool.com must have got good traffic

thirdly:
domains like ciul.com, cool.com(whatever spelling variations) will be sold at a very good price

lastly:
Cuil.com got popularly criticized(more criticism.. more popularity)
People may remember this search engine(or its launch) for a while

If you are troubleshooting strange errors where a command is behaving in a restricted manner then, SELINUX 'enforcing' settings can be the cause. SELINUX enforces security.
For instance:
On calling /usr/bin/crontab <filename> from a terminal after logging in as apache user -> No error.
On calling /usr/bin/crontab <filename> from php/apache running as apache user -> Error like
cron/tmp.XXXX9IOQnL: Permission denied

Troubleshoot:
Checking apache log,
[root@myhost ~]# tail -f /var/log/httpd/error_log
cron/tmp.XXXX6lUoXL: Permission denied

Cheking syslog,
[root@myhost ~]# tail /var/log/cron
Jul 17 16:01:18 myhost kernel: audit(1216310478.752:1273): avc:  denied  { setgid } for  pid=16238 comm="crontab" capability=6 scontext=root:system_r:httpd_sys_script_t tcontext=root:system_r:httpd_sys_script_t tclass=capability
Jul 17 16:01:18 myhost kernel: audit(1216310478.752:1274): avc:  denied  { setuid } for  pid=16238 comm="crontab" capability=7 scontext=root:system_r:httpd_sys_script_t tcontext=root:system_r:httpd_sys_script_t tclass=capability
Jul 17 16:01:18 myhost kernel: audit(1216310478.752:1275): avc:  denied  { write } for  pid=16238 comm="crontab" name="cron" dev=sda2 ino=392461 scontext=root:system_r:httpd_sys_script_t tcontext=system_u:object_r:var_spool_t tclass=dir
 

Checking for correct permissions,
[root@myhost ~]# ls -l /usr/bin/crontab
-rwsr-xr-x  1 root root 70592 Jul 11  2005 /usr/bin/crontab
Its correct.
[root@myhost ~]# ls -ld /var/spool/cron
drwx------  2 root root 4096 Jul 17 15:40 /var/spool/cron
Its correct.

Checking selinux setting,
[root@myhost ~]#  cat /selinux/enforce
1
[root@myhost ~]#  cat /etc/selinux/config 

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#       enforcing - SELinux security policy is enforced.
#       permissive - SELinux prints warnings instead of enforcing.
#       disabled - SELinux is fully disabled.
SELINUX=enforcing
# SELINUXTYPE= type of policy in use. Possible values are:
#       targeted - Only targeted network daemons are protected.
#       strict - Full SELinux protection.
SELINUXTYPE=targeted 

Resoultion:

If you are allowed to diable selinux then: 

Temporarily, disable selinux without reboot: 

Else,

After testing the following strategies of MySQL cluster alternatives, here, are my supplies to open source communities, with out which I could not have tried the following in first place. I have consolidated what I found on net in bits and pieces + some of my experiences.

1. MySQL Clustering(ndb-cluster stogare)
2. MySQL / GFS-GNBD/ HA
3. MySQL / DRBD /HA
4. MySQL Write Master / Multiple MySQL Read Slaves
5. Standalone MySQL Servers(Functionally seperated)

• MySQL Clustering(ndb-cluster stogare) (Active/Active)
  

• MySQL / GFS-GNBD/ HA (Active/Passive)
  

• MySQL / DRBD / HA (Active/Passive)

• MySQL Write Master / Multiple MySQL Read Slaves (Active/Active)

• Standalone MySQL Servers(Functionally seperated) (Active)
  

5 comments:

Ben said...

Fascinating comparison, thanks for the work.

There are some other disadvantages with the clustering which MySql:
1. No big transactions.
2. Range selection performance is bad. Consider a traditional MySql in parallel if you need to select ranges of data. However, single rows selected by a key offer excellent performance.
3. Bad latency.

There is a miss-conception that MySql clustering is MySql, but available. This is not the case :)

April 28, 2007 9:59 AM  

Ben said...

MySql replication.

This offers excellent performance and very low latency between master and replication.

However Reads are not HA as mentioned in the article. You require another application to make reads HA. For example a load-balancer.

Fall-over is a simple matter, but needs careful set-up to ensure replication is changed from read-only to read-write.

However resetting the system for another fall-over after a fall-over, is manual and can be difficult, especially with a large database.

April 28, 2007 10:08 AM  

Praveen Kumar K.S said...

Thanks.

I bet the best one is:

A)MySQL-HA-DRBD(Actve/passive) setup as Master

B)Slave1, Slave2, .... Slave'n' in a load balanced setup.

'A' will be available over an VIP say 192.168.0.1

'B' will be available over an VIP say 192.168.0.2

Now, in your application, use,

-->mysql connection to 198.168.0.1 for DB writes

-->mysql connection to 198.168.0.2 fro DB reads


This gives us HA WRITES and HA/Load shared READS.

Cheers,
Praveen.

April 29, 2007 7:01 AM  

 

LVS/NAT usage scenarios:

What?

Assume you need to provide high available and load balanced service(http,mysql,ftp,etc).
To make any service high availed, we, require at least 2 nodes running that service.
We shall call this "realserver" or "RS".

Plus, we need a node to direct the load to these nodes in a balanced way.
We shall call this "loaddirector" or "LD".
We require atleast two such LD to make load-sharing mechanism, highly available.

You will have to prepare ground work on Routes, Load balanced ports, Direct ports and Application perspective. Lets, discuss this with an example.



Load balanced VIP and virtual ports:
66.94.234.144:80 (can be used for http globally)
|_192.168.100.8:80
|_192.168.100.9:80
192.168.100.2:80 (can be used for http locally)
|_192.168.100.8:80
|_192.168.100.9:80
192.168.100.2:10022 (can be used to scp data to shared disk with in LAN)
|_192.168.100.8:22
|_192.168.100.9:22
192.168.100.2:10044 (some service)
|_192.168.100.8:1234
|_192.168.100.9:1234
Non Load balanced VIP and virtual ports:
192.168.100.3:3306 (mysql service)

Routes and gateway:
Host-----------------------------------Gateway--------------Route

LD1-------------------------------------192.168.100.1---------All
LD2-------------------------------------192.168.100.1---------All
Apache1-----------------------------192.168.100.2---------192.168.100.9, 192.168.100.10
Apache2 ----------------------------192.168.100.2---------192.168.100.8, 192.168.100.10
GNBD---------------------------------192.168.100.2---------192.168.100.8, 192.168.100.9
MySQL/HA/DRBD1--------------192.168.100.1---------All
MySQL/HA/DRBD2--------------192.168.100.1---------All


[Note: 1
Apaches and GNBD are below the NAT.
Thier gateway is Internal VIP provided by LDs.
If, you don't delete direct route to the world on Apache:

1. Internal LAN client (192.168.100.46) requests 192.168.100.2:80
2. LD forwards it to 192.168.100.8:80
3. Apache1 processes the requests.
4. Apache1 sees that there is direct route to 192.168.100.46
5. Tries to communicate directly bypassing LD.
6. Connection hangs.

2 comments:

Anonymous said...

Greate articles. Keep up your good work :)

April 19, 2007 3:05 PM  

Praveen Kumar K.S said...

Thanks.

April 20, 2007 5:37 AM

Howto MySQL DRBD HA:

This is one of the MySQL High Availability strategy I had discussed earlier. I have consolidated what I found on net in bits and pieces + some of my experiences. Here are some tips to get it working.
In this approach, I have noticed that the failover is smooth and quick. If you are looking only for High Availability of MySQL resources, then
, this is the one.

Env:
I tried CentOS release 4.4 (Final) x86_64 on 2 servers.
One which has a better RAM can be used as a active node. Other, can be considered the failover.

Partitioning during OS installtion:
You need to reserve a huge physical volume which would be later used as a DRBD volume.
Don't specify any file system type.

fdisk /dev/sda

Should print:

The number of cylinders for this disk is set to 9729.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 2611 20972826 83 Linux
/dev/sda2 2612 2872 2096482+ 82 Linux swap
/dev/sda3 2873 3003 1052257+ 8e Linux LVM
/dev/sda4 3004 9729 54026595 5 Extended
/dev/sda5 3004 9729 54026563+ 8e Linux LVM

We are going to use /dev/sda5 as a DRBD device.


DRBD:

Installation:
On machine1 and machine2

• Install it as you wish.

• You can do an RPM based or a BINARY or a SOURCE compilation.

• IMPORTANT:(Crucial for failover) Heartbeat uses either LSB Resource Agents or OCF Resource Agents or Heartbeat Resource Agents to start and stop heartbeat resources. Here, MySQL,DRBD and IP are our heartbeat resources.
  

• Refer thi page on Resource Agent

• As you are aware of it many *nix services are started using LSB Resource Agents. They are found in /etc/init.d
• A service is started/stopped using: /etc/init.d/servicename start/stop/status
  

• You should see to it that you have similar LSB Resource Agent for MySQL.

• In, source based installation it will be created in $PREFIX/share directory as mysql.server. $PREFIX is one you give during source compilation.
  

• Fix that script and copy it to /etc/init.d/

• In case of RPM based installation you will get LSB Resource Agent in place.

• End objective is that, MySQL should be up and running.

• Stop MySQL.

• Move your data directory to a directory on DRBD share.

• Later, create a softlink.

• This is how I would have done assuming my initial data directory was /home/mysql/data :

13 comments:

Irwan said...

Great article!
I'm blogging about DRBD for MySQL too.

June 07, 2007 1:57 AM  

Anonymous said...

Good article, but why do you need LVS? Aren't DRDB and the IP addr sufficient for MySQL?

July 17, 2007 3:13 PM  

ku3_p417ch0n6 said...

LVS needed because Kumar using virtual IP for his mysql server.

November 29, 2007 11:49 PM  

Anonymous said...

i have some error " Lower device is already claimed drbd cmd 'drbdsetup /dev/drbd0 disk /dev/sda6 /dev/sda6 internal --set-defaults --create-device --on-io-error=detach'. how to solve this problem? i have 2 resources in drbd.conf. can i use Kumar's step setup same this above document? thank you

January 16, 2008 1:44 AM  

tompata said...

Is there anybody tried to install / test MySQL DRBD on virtual machines (example: vmware)?

January 29, 2008 1:21 AM  

pannu said...

Great article.
I have one question.. if my data volume or the drdb volume where mysql will keep the data is on a SAN partition connected to machine 1.

February 02, 2008 3:28 AM  

kerneloverdrive said...

Hi,

Is it possible to use to virutal IPs for the mysql-drdb-ha box?

ex. 192.168.0.1 - Local
100.100.100.1 - External

where both ip's will cater mysql services and also replicate to local and remote slaves.

February 13, 2008 8:35 PM  

kerneloverdrive said...

mybad: that's -- possible to use "two" or more virtual IP's...

February 13, 2008 8:37 PM  

Praveen Kumar K.S said...

@kerneloverdrive:

Ya.. you can use more that one VIP.
In haresources file you can mention VIP per eth device.

i.e

IPaddr2::192.168.0.1/24/eth0
IPaddr2::100.100.100.1/24/eth1

The MySQL service will be availed on both IP's for sure.

February 13, 2008 10:58 PM  

Praveen Kumar K.S said...

@ pannu:

If you have a SAN.. Why you have to go for DRBD HA. Instead go for RedHat Cluster with SAN to be used as a shared data volume for multiple MySQL. Thereby you get HA and load balancing.

February 13, 2008 11:00 PM  

kerneloverdrive said...

Hi Praveen,

Thanks for the help. Will try implementing this setup asap.

when I can get a copy of RHEL, will try it with SAN/NAS and so that I can have a real HPC/HA MySQL Cluster.

February 14, 2008 7:20 AM  

Suhas said...

Hi Praveen,
I have configured MySQL DRBD / HA it's working great.. I also made Slave for VIP. this is really works fine for us.
we are using 32 bit CentOS.

Thanks
~Pandit

March 03, 2008 3:58 AM  

Praveen Kumar K.S said...

Nice to know that 'HA-Master replicating to slave' is working fine. Cheers!

March 04, 2008 12:23 PM