Note:  you only have to do the following installations on the server where you are doing the mounts on.

Let us download and install the filesystem framework which is a requirement for sshfs called fuse.

wget http://voxel.dl.sourceforge.net/sourceforge/fuse/fuse-2.7.4.tar.gz
tar zxpfv fuse-*.gz
cd fuse*
./configure

If you get the following error, you will either have to point to the location of the kernel source or install it if needed.

checking kernel source directory... Not found
configure: error:
*** Please specify the location of the kernel source with
*** the '--with-kernel=SRCDIR' option
configure: error: ./configure failed for kernel

In our case here, we will be installing the source using yum.

yum -y install kernel-devel

Once installed, you will have to find out the directory it is installed in

ls -l /usr/src/kernels/
total 4.0K
drwxr-xr-x 18 root root 4.0K Oct  7 14:50 2.6.18-92.1.13.el5-x86_64/

./configure --with-kernel=/usr/src/kernels/2.6.18-92.1.13.el5-x86_64
make && make install
cd ..

Now let us get sshfs source and install it.

wget http://voxel.dl.sourceforge.net/sourceforge/fuse/sshfs-fuse-2.1.tar.gz
tar zxpfv sshfs*
cd sshfs-fuse-*
./configure

If you get the following error:

checking for SSHFS... configure: error: The pkg-config script could not be found or is too old.  Make sure it
is in your PATH or set the PKG_CONFIG environment variable to the full
path to pkg-config.

OR

checking for SSHFS... configure: error: Package requirements (fuse >= 2.2 glib-2.0 gthread-2.0) were not met:

No package ‘glib-2.0′ found
No package ‘gthread-2.0′ found

You need to install glib2.  Do the following:

yum install glib2-devel

Once installation is done, continue with configure.

./configure
make && make install

After installation is done, we can move on with testing the installation:

cd /mnt
mkdir test
sshfs 10.0.0.2:/ test

If you get the following error,
sshfs: error while loading shared libraries: libfuse.so.2: cannot open shared object file: No such file or directory
execute this: NOTE: this is for x64 system. If you have 32 bit system, you have to symlink to /lib instead.
ln -s /usr/local/lib/libfuse.so.2 /lib64/
Let us try mounting again:
sshfs 10.0.0.2:/ test
At this point it would be like if you were making a ssh connection to 10.0.0.2 You will have to type in a password to get the mount to happen. You may get the following error: fuse: device not found, try 'modprobe fuse' first

If you do ‘modprobe fuse’, as they tell you to, and you get:
modprobe fuse
FATAL: Module fuse not found.

That means your running kernel is not the same version as the one you compiled with. You have two options here:
1) you can upgrade your kernel by typing: yum update kernel
2) find the source files for the kernel you have running and recompile fuse.

I went with option 1. Once you do the update, reboot and try doing modprobe fuse again.

At this point we can try doing the mount again.
cd /mnt
sshfs 10.0.0.2:/ test

If you do not get any errors, do df -h to see the mount:
...
sshfs#10.0.0.2:/ 1000G 0 1000G 0% /mnt/test
...

At this point you can browse 10.0.0.2 server filesystem as it was local on your server.

————————————-

DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

Following command will search for the string you specified. Generally this will give you all of the packages which has specified string in title or description. Most of the time you will have to look through a lot of output to find what you are looking for.

yum search string

Probably one of the most important options for yum is provides/whatprovides. If you know what command you need, you can find out what package you have to install in order to have that command available to you.

yum provides (or whatprovides) command

Following command is same as above but with less output.

yum -d 1 provides command

So for example if you are trying to figure out what you need to install to use bunzip2, type:

yum -d 1 provides bunzip2

you will get a similar output as below.

# yum -d 1 provides bunzip2
bzip2.x86_64 1.0.2-13.EL4.3 base
bzip2.x86_64 1.0.2-13.EL4.3 base
man-pages-fr.noarch 0.9.7-13.el4 base
man-pages-ja.noarch 20050215-2.EL4.3 base
man-pages-pl.noarch 0.23-5 base

As you can see bunzip2 is part of bzip2 package. So now you can you just install bzip2.x86_64 to get bunzip2.

To learn more about what else is available, read man yum.

Note: you must be logged in as root to do following.

vi /etc/passwd
find joe and change it to john, save/exit

vi /etc/group
find joe and change it to john, save/exit

vi /etc/shadow
find joe and change it to john. This file is read only and you have to force overwrite it. In vi it is :w! once saved, quit.

cd /home
mv joe john

And that should do the trick.

[Edited] Right after I posted this post, I was contacted and was told to look at utility called usermod. Read more about it man usermod. Got to love the quick responses.

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

Master1 server ip: 10.0.0.1
Master2 server ip: 10.0.0.2
Slave username: slaveuser
Slave pw: slavepw
Your data directory is: /usr/local/mysql/var/

Let us go through the steps you must take on Master1 to enable it to act as master and slave by using following configuration which goes under [mysqld] section:

# let's make it so auto increment columns behave by having different increments on both servers
auto_increment_increment=2
auto_increment_offset=1
# Replication Master Server
# binary logging is required for replication
log-bin=master1-bin
binlog-ignore-db=mysql
binlog-ignore-db=test
# required unique id between 1 and 2^32 - 1
server-id = 1
#following is the slave settings so this server can connect to master2
master-host = 10.0.0.2
master-user = slaveuser
master-password = slavepw
master-port = 3306

Following is the configuration which goes on master2 under [mysqld] section:

# let's make it so auto increment columns behave by having different increments on both servers
auto_increment_increment=2
auto_increment_offset=2
# Replication Master Server
# binary logging is required for replication
log-bin=master2-bin
binlog-ignore-db=mysql
binlog-ignore-db=test
# required unique id between 1 and 2^32 - 1
server-id = 2
#following is the slave settings so this server can connect to master2
master-host = 10.0.0.1
master-user = slaveuser
master-password = slavepw
master-port = 3306

On master1 server, go to mysql> prompt and add the appropriate user:

mysql> grant replication slave on *.* to slaveuser@'10.0.0.2' identified by 'slavepw';

On master2 server do the same but allow right ip:

mysql> grant replication slave on *.* to slaveuser@'10.0.0.1' identified by 'slavepw';

Restart both of the master servers and check slave status:

mysql> show slave status\G

That is all you have to do to set up the replication. Of course there are a lot more configuration options but this should get your replication going and you can tweak from here on.

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

1) Offload some of the queries from one server to another and spread the load: One of the biggest advantages to have master-slave set up in MySQL is to be able to use master for all of the inserts and send some, if not all, select queries to slave. This will most probably speed up your application without having to diving into optimizing all the queries or buying more hardware.

2) Do backups from slave: One of the advantages people overlook is that you can use MySQL slave to do backups from. That way site is not affected at all when doing backups. This becomes a big deal when your database has grown to multiple gigs and every time you do backups using mysqldump, site lags when table locks happen. For some sites, this could mean that site goes down for few secs to minutes. If you have slave, you just take slave out of rotation (should be built into code) and run backups off the slave. You can even stop slave MySQL instance and copy the var folder instead of doing mysqldump.

Ok let us dive into how to setup master-slave replication under MySQL. There are many configuration changes you can do to optimize your MySQL set up. I will just touch on very basic ones to get the replication to work. Here are some assumptions:

Master server ip: 10.0.0.1
Slave server ip: 10.0.0.2
Slave username: slaveuser
Slave pw: slavepw
Your data directory is: /usr/local/mysql/var/

Put the following in your master my.cnf file under [mysqld] section:

# changes made to do master
server-id = 1
relay-log = /usr/local/mysql/var/mysql-relay-bin
relay-log-index = /usr/local/mysql/var/mysql-relay-bin.index
log-error = /usr/local/mysql/var/mysql.err
master-info-file = /usr/local/mysql/var/mysql-master.info
relay-log-info-file = /usr/local/mysql/var/mysql-relay-log.info
datadir = /usr/local/mysql/var
log-bin = /usr/local/mysql/var/mysql-bin
# end master

Copy the following to slave’s my.cnf under [mysqld] section:

# changes made to do slave
server-id = 2
relay-log = /usr/local/mysql/var/mysql-relay-bin
relay-log-index = /usr/local/mysql/var/mysql-relay-bin.index
log-error = /usr/local/mysql/var/mysql.err
master-info-file = /usr/local/mysql/var/mysql-master.info
relay-log-info-file = /usr/local/mysql/var/mysql-relay-log.info
datadir = /usr/local/mysql/var
# end slave setup

Create user on master:
mysql> grant replication slave on *.* to slaveuser@'10.0.0.2' identified by 'slavepw';

Do a dump of data to move to slave
mysqldump -u root --all-databases --single-transaction --master-data=1 > masterdump.sql

import dump on slave
mysql < masterdump.sql

After dump is imported go in to mysql client by typing mysql. Let us tell the slave which master to connect to and what login/password to use:
mysql> CHANGE MASTER TO MASTER_HOST='10.0.0.1', MASTER_USER='slaveuser', MASTER_PASSWORD='slavepw';

Let us start the slave:
mysql> start slave;

You can check the status of the slave by typing
mysql> show slave status\G

The last row tells you how many seconds its behind the master. Don’t worry if it doesn’t say 0, the number should be going down over time until it catches up with master (at that time it will show Seconds_Behind_Master: 0) If it shows NULL, it could be that slave is not started (you can start by typing: start slave) or it could be that it ran into an error (shows up in Last_errno: and Last_error under show slave status\G).

Related posts:

• How do I dump all tables in a database into separate files?
• How do I import individual table dump files in to MySQL using shell script?
• MySQL backups using mysqldump

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

python -V

Let us download and install readline:

wget ftp://ftp.cwru.edu/pub/bash/readline-5.2.tar.gz
tar zxf readline-5.2.tar.gz
cd readline-5.2
./configure
make install

Now let us install python with readline support:

wget http://www.python.org/ftp/python/2.5.1/Python-2.5.1.tgz
tar zxf Python-2.5.1.tgz
cd Python-2.5.1


I had some problems on one of the servers where it would not compile readline support in to python. I was able to compile reading support in to python by:

echo "readline readline.c -lreadline -ltermcap" >> Modules/Setup.local

Now let us continue with python installation.

./configure --prefix=/usr/local/python-2.5.1 --enable-readline
make -i install

If you do not do “make -i install”, install may fail with following error (-i means ignore any errors):
Compiling /usr/lib/python2.5/zipfile.py ...
make: *** [libinstall] Error 1

If you scroll up, you will find following error which seems to be the root cause:

Compiling /usr/lib/python2.5/test/test_multibytecodec.py ...
Sorry: UnicodeError: ("\\N escapes not supported (can't load unicodedata module)",)

Once you do python install with make -i install, that library (unicodedata.so which is not built until later stage of build process) gets installed. If you want, you can type make install once again (without ignoring errors) and it will complete without errors.

Once you have python installed, you would want to use the new version. I like to keep a backup of old files in case I have to use older version for any reason. Run following which creates symbolic links and makes backups of current files:

for binaries in `find /usr/local/python-2.5.1/bin/*` ; do
mv /usr/bin/`basename ${binaries}` /usr/bin/`basename ${binaries}`.bak
ln -s ${binaries} /usr/bin/`basename ${binaries}`
done

Now let us get phpsh and try it out:

wget http://www.phpsh.org/phpsh-latest.tgz
tar zxf phpsh-latest.tgz
cd ../phpsh
chmod +x phpsh
./phpsh

At this point you should be at the shell: php>

Following is a snippet from README file which comes with phpsh. You should take a look since it has more details on how to use phpsh:

Type php commands and they will be evaluated each time you hit enter. Ex:
php> $msg = "hello world"
Put = at the beginning of a line as syntactic sugar for return. Ex:
php> = 2 + 2
If you end a line with a backlash (\), you can enter multi-line input.
For example,
php> print "like \
... this"
like this
php>

There we go. Now you have a great interactive php shell prompt. Note that there is interactive mode built into php as well. I personally do not like it as much but you can try it out for yourself by typing:

php -a
Interactive mode enabled
echo "Hello world";
Hello world

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

#!/bin/bash
db=$1
if [ "$db" = "" ]; then
echo "Usage: $0 db_name"
exit 1
fi
mkdir done
clear
for sql_file in *.sql; do
echo "Importing $sql_file";
mysql $db< $sql_file;
mv $sql_file done;
done

Related posts:

• How do I dump all tables in a database into separate files?
• MySQL backups using mysqldump

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

mkdir /backups/repos -p
for repostobackup in `ls /svn/` ; do
filename=`basename ${repostobackup}`
if [ ! $filename = "" ]; then
hot-backup.py --archive-type=bz2 /svn/${filename} /backups/repos
fi
done

This will create your backup files and compress them using bzip2. You can also use zip or gz if you prefer. Another thing you should do is to edit the hot-backup.py script and change num_backups to be whatever you think is a good number. I personally use: num_backups = 10

That’s all there is to it. Just add this script to your crons and your backups will be automated. You may want to consider moving your backups to another server by adding ftp, scp or rsync at the end of the script.

On server1, you type: ssh-keygen -t rsa (just press enter to keep accepting defaults). You should see something like this:

ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
a2:b2:aw:w2:63:25:2a:62:fs:d5:ff:fd:11:f1:aa:60 root@server1

Fingerprint for your server will be different. Now cat /root/.ssh/id_rsa.pub Copy the contents it displays. You will need this for server2. Paste it into notepad or any other text editor and make sure it pastes as one line. This is very crucial you check this.

Now login to server2. Create the public key by typing: ssh-keygen -t rsa (this is same thing we did on server1). Once you are done, type vi /root/.ssh/authorized_keys2

Paste the content you copied earlier on server1. Make sure it is all on one line. Save/exit.  At this point, we should change the permissions on the file to make sure sshd likes it:  chmod 600 /root/.ssh/authorized_keys2

Go back to server1 and type ssh server2 You should be logged in with out having to put in a password. If you are prompted for password still, check server2 /root/.ssh/authorized_keys2 file and make sure everything you pasted is one line.

That is all you have to do set up public key authentication over ssh!

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

Let us dive into this. First we create user and set up directory structure.

echo "named:x:200:200:Nameserver:/chroot/named:/bin/false" >> /etc/passwd
echo "named:x:200:" >> /etc/group
mkdir -p /chroot/named
cd /chroot/named
mkdir -p dev etc/namedb/slave var/run
chown -R named:named /chroot/named/etc/namedb/slave
chown named:named /chroot/named/var/run
mknod /chroot/named/dev/null c 1 3
mknod /chroot/named/dev/random c 1 8
chmod 666 /chroot/named/dev/{null,random}
cp /etc/localtime /chroot/named/etc/

vi /etc/sysconfig/syslog
edit the line which starts with SYSLOGD_OPTIONS and edit it to look like: SYSLOGD_OPTIONS=”-m 0 -a /chroot/named/dev/log”
Let us restart syslog to use new settings and let us secure the physical files on the server.

/etc/rc.d/init.d/syslog stop
/etc/rc.d/init.d/syslog start
chown root /chroot
chmod 700 /chroot
chown named:named /chroot/named
chmod 700 /chroot/named
cd /chroot/named
chattr +i etc/localtime var

Let us clean up previous bind install since most linux installations have named (bind) pre-installed.

rpm -qa |grep bind
rpm -e --nodeps <copy-paste-all-the-packages-separated-by-space>

Let us get the source files for bind and install it. At time of writing, bind 9.4.1 is the latest.

wget http://ftp.isc.org/isc/bind9/9.4.1/bind-9.4.1.tar.gz
tar zxpfv bind-*.gz
cd bind*
./configure
make && make install

copy following content to /etc/init.d/named

#!/bin/sh
#
# named This shell script takes care of starting and stopping
# named (BIND DNS server).
#
# chkconfig: 345 55 45
# description: named (BIND) is a Domain Name Server (DNS) \
# that is used to resolve host names to IP addresses.
# probe: true
#
# Source function library.
. /etc/rc.d/init.d/functions
#
# Source networking configuration.
. /etc/sysconfig/network
#
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
#
[ -f /usr/local/sbin/named ] || exit 0
[ -f /chroot/named/etc/named.conf ] || exit 0
#
# See how we were called.
case "$1" in
start)
# Start daemons.
echo -n "Starting named: "
daemon /usr/local/sbin/named -u named -t /chroot/named -c /etc/named.conf
echo
touch /var/lock/subsys/named
;;
stop)
# Stop daemons.
echo -n "Shutting down named: "
kill `pidof named`
echo
rm -f /var/lock/subsys/named
;;
status)
status named
exit $?
;;
restart)
$0 stop
$0 start
exit $?
;;
reload)
/usr/local/sbin/rndc reload
exit $?
;;
probe)
# named knows how to reload intelligently; we don't want linuxconf
# to offer to restart every time
/usr/local/sbin/rndc reload >/dev/null 2>&1 || echo start
exit 0
;;
#
*)
echo "Usage: named {start|stop|status|restart|reload}"
exit 1
esac
#
exit 0

Make it executable: chmod +x /etc/init.d/named
Let us set it so “named” will automatically start at boot up: chkconfig --add named

Save follow code into /chroot/named/etc/named.conf
options {
recursion no; // this will disable lookups against our server recursion no;
directory "/etc/namedb"; // Working directory
pid-file "/var/run/named.pid"; // Put pid file in working dir
forwarders {
10.10.10.10; //ip of dns server to forward requests to
};
statistics-file "/var/run/named.stats";
query-source address * port 53;
version "Bind 10";
};
controls {
inet 127.0.0.1 port 953
allow { 127.0.0.1; } keys { "rndc-key"; };
};
// Root server hints
zone "." {
type hint;
file "root.hint";
};
// Provide a reverse mapping for the loopback address 127.0.0.1
zone "0.0.127.in-addr.arpa" {
type master;
file "db.127.0.0";
notify no;
};

Save following in /chroot/named/etc/namedb/root.hint

; This file holds the information on root name servers needed to
; initialize cache of Internet domain name servers
; (e.g. reference this file in the "cache . <file>"
; configuration file of BIND domain name servers).
;
; This file is made available by InterNIC
; under anonymous FTP as
; file /domain/named.root
; on server FTP.INTERNIC.NET
;
; last update: Nov 5, 2002
; related version of root zone: 2002110501
;
;
; formerly NS.INTERNIC.NET
;
. 3600000 IN NS A.ROOT-SERVERS.NET.
A.ROOT-SERVERS.NET. 3600000 A 198.41.0.4
;
; formerly NS1.ISI.EDU
;
. 3600000 NS B.ROOT-SERVERS.NET.
B.ROOT-SERVERS.NET. 3600000 A 128.9.0.107
;
; formerly C.PSI.NET
;
. 3600000 NS C.ROOT-SERVERS.NET.
C.ROOT-SERVERS.NET. 3600000 A 192.33.4.12
;
; formerly TERP.UMD.EDU
;
. 3600000 NS D.ROOT-SERVERS.NET.
D.ROOT-SERVERS.NET. 3600000 A 128.8.10.90
;
; formerly NS.NASA.GOV
;
. 3600000 NS E.ROOT-SERVERS.NET.
E.ROOT-SERVERS.NET. 3600000 A 192.203.230.10
;
; formerly NS.ISC.ORG
;
. 3600000 NS F.ROOT-SERVERS.NET.
F.ROOT-SERVERS.NET. 3600000 A 192.5.5.241
;
; formerly NS.NIC.DDN.MIL
;
. 3600000 NS G.ROOT-SERVERS.NET.
G.ROOT-SERVERS.NET. 3600000 A 192.112.36.4
;
; formerly AOS.ARL.ARMY.MIL
;
. 3600000 NS H.ROOT-SERVERS.NET.
H.ROOT-SERVERS.NET. 3600000 A 128.63.2.53
;
; formerly NIC.NORDU.NET
;
. 3600000 NS I.ROOT-SERVERS.NET.
I.ROOT-SERVERS.NET. 3600000 A 192.36.148.17
;
; operated by VeriSign, Inc.
;
. 3600000 NS J.ROOT-SERVERS.NET.
J.ROOT-SERVERS.NET. 3600000 A 192.58.128.30
;
; housed in LINX, operated by RIPE NCC
;
. 3600000 NS K.ROOT-SERVERS.NET.
K.ROOT-SERVERS.NET. 3600000 A 193.0.14.129
;
; operated by IANA
;
. 3600000 NS L.ROOT-SERVERS.NET.
L.ROOT-SERVERS.NET. 3600000 A 198.32.64.12
;
; housed in Japan, operated by WIDE
;
. 3600000 NS M.ROOT-SERVERS.NET.
M.ROOT-SERVERS.NET. 3600000 A 202.12.27.33
; End of File

This should get you started. Now just create appropriate zone files and you are good to go.

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

# dmesg | grep RAMDISK
RAMDISK driver initialized: 16 RAM disks of 16384K size 1024 blocksize

You should get above output on CentOS and RHEL.  Other linux flavors will have similar output as well.  If you would like to see how they are named and what you would need to refer to, do the following:

# ls -l /dev/ram*
lrwxrwxrwx 1 root root 4 Apr 24 12:05 /dev/ram -> ram1
brw-rw---- 1 root disk 1, 0 Apr 24 12:05 /dev/ram0
brw-rw---- 1 root disk 1, 1 Apr 24 12:05 /dev/ram1
brw-rw---- 1 root disk 1, 10 Apr 24 12:05 /dev/ram10
brw-rw---- 1 root disk 1, 11 Apr 24 12:05 /dev/ram11
brw-rw---- 1 root disk 1, 12 Apr 24 12:05 /dev/ram12
brw-rw---- 1 root disk 1, 13 Apr 24 12:05 /dev/ram13
brw-rw---- 1 root disk 1, 14 Apr 24 12:05 /dev/ram14
brw-rw---- 1 root disk 1, 15 Apr 24 12:05 /dev/ram15
brw-rw---- 1 root disk 1, 2 Apr 24 12:05 /dev/ram2
brw-rw---- 1 root disk 1, 3 Apr 24 12:05 /dev/ram3
brw-rw---- 1 root disk 1, 4 Apr 24 12:05 /dev/ram4
brw-rw---- 1 root disk 1, 5 Apr 24 12:05 /dev/ram5
brw-rw---- 1 root disk 1, 6 Apr 24 12:05 /dev/ram6
brw-rw---- 1 root disk 1, 7 Apr 24 12:05 /dev/ram7
brw-rw---- 1 root disk 1, 8 Apr 24 12:05 /dev/ram8
brw-rw---- 1 root disk 1, 9 Apr 24 12:05 /dev/ram9
lrwxrwxrwx 1 root root 4 Apr 24 12:05 /dev/ramdisk -> ram0

All those ramdisks listed have same size.  In above example, they are all 16MB.  Let us change that so we have more space allowed.  Note that I say allowed and not allocated.  We allocate space in one of the later steps by formatting one of the drives above.   Let us set it up so we have 128 MB.  Since this has to be in multiples of 1024, we will setup Ramdisk to have 131072K. 

vi /etc/grub.conf

Find first line which looks similar to following:

kernel /vmlinuz-2.6.9-42.0.10.EL ro root=/dev/VolGroup00/LogVol00

add ramdisk_size=131072 to the end of the line.  Now your line should look like:

kernel /vmlinuz-2.6.9-42.0.10.EL ro root=/dev/VolGroup00/LogVol00 ramdisk_size=131072 Save and exit grub.conf.  At this point you have it configured to have ramdisk with new size but it does not take effect until you reboot your system.  Once you have rebooted your system, we can start doing rest of configurations.

mke2fs -m 0 /dev/ram0

This will format the ram0 ramdrive for us to use. At this point, kernel will allocate space for you.  Let us setup Ramdisk mount point so we can use it.  We will also have it be owned by user “sunny” so that user can read/write to that mount.

mkdir /home/ramdisk
mount /dev/ram0 /home/ramdisk
chown sunny.sunny /home/ramdisk

At this point you should be able to type:  mount and see your new Ramdisk drive mounted on /home/ramdisk

Remember that everything you put on this drive will be gone if you reboot your server.  If you unmounted the Ramdisk drive and remounted it, your files will still be there.  It is because your system has that much ram set aside for your Ramdisk and will not use it for anything else.   If you would like to setup Ramdisk the same next time you boot up, add these lines to your /etc/rc.local files.

mke2fs -m 0 /dev/ram0
mount /dev/ram0 /home/ramdisk
chown sunny.sunny /home/ramdisk

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

YUM Install 

Easiest way to install subversion is via “yum” by typing:

yum install subversion

Once install is done, confirm it by typing “svn” at the prompt and you should get:

Type 'svn help' for usage.

At this point you can skip to “Setting up Subversion repository” part.

SOURCE Install

Obtain source from:  Subversion.  At the time of writing, latest (1.4.3) version can be obtain from this link:  http://subversion.tigris.org/downloads/subversion-1.4.3.tar.gz

tar zxf subversion*
cd subversion*
./configure
make && make install

after everything goes well, type svn at the prompt and you should get:

Type 'svn help' for usage.

Setting up Subversion repository

adduser svnusers
mkdir repos/branches -p
mkdir repos/trunk -p
mkdir repos/tags -p
mkdir /svn
svnadmin create /svn/demorepo
svn import --message "Initial set up" repos file:///svn/demorepo
cd /svn/demorepo
chown .svnusers . -R
chmod 775 * -R
chmod +s db

Thats all there is to it to setup Subversion repository.  At this point, you should add any users you want to have access to the repository by adding them to “svnusers” group.

————————————-
DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

rsync -ae ssh server1:/home /home/backups/server1_home_backup/

This command will download all the files/directories from /home on server1 and copies them to /home/backups/server1_home_backup/
-a = archive mode. This will preserve permissions, timestamps, etc.
-e = specify which remote shell to use. In our case, we want to use ssh which follow right after “e”

Let us improve on this and add couple more parameters:

rsync -zave ssh --progress server1:/home /home/backups/server1_home_backup/
-z = adds zip compression.
-v = verbose
–progress = my favorite parameter when I am doing rsync manually, not so good when you have it in cron. This show progress (how_many_files_left/how_many_files_total) and speed along with some other useful data.

Great.. we are moving along pretty good. Let us add some security to make sure things work the way we want to.

rsync --delete-after -zave ssh --progress server1:/home /home/backups/server1_home_backup/

–delete-after = this will delete files on backup server which are missing from source after ALL syncing is done. If you don’t care of having extra files on your backup server and have plenty of disk space to spare, do not use this parameter.

Lastly, one of the VERY handy parameters,

rsync --delete-after -zave ssh --progress server1:/home /home/backups/server1_home_backup/ -n

The -n (or –dry-run) parameter is great to use for testing. It will not transfer or delete any files, rather will report to you what it would have done if it was ran with out -n parameter. This way you can test it with out destroying or transfering data just to find out that is not what you wanted.

For further reading: man rsync

If you are on 64 bit system, you will get errors, lots of them.  I went through and fixed “some” errors by modifying code but it was just taking too much time so I decided not to go 64 bit route.  But below are the efforts I made.  Maybe somebody can help with rest of the steps.   Following instructions work fine with 32 bit systems. For more help look at the MCache Handbook.
Thank you Mohawk Software for all your efforts developing this!

Web site: http://www.mohawksoft.org/?q=node/32
PHP reference:  http://us2.php.net/manual/en/ref.msession.php

yum install ncurses-devel #otherwise you might see errors about no such file curses.h

wget http://www.mohawksoft.org/download/mcache-070415-M2.0b6.tar.gz
wget http://www.mohawksoft.org/download/phoenix-070415-M2.0b6.tar.gz
tar zxf mcache*.gz
tar zxf phoenix*.gz
cd phoenix
ln -s Linux.mak config/config.mak
make dirs
make links
make butils
export PATH=$PATH:/opt/mohawk/bin
make libs
vi sqldrv/Makefile # about line 24, comment out POSTGRES=1 and ODBC=1
cd ../mcac*
make server
vi tools/Makefile # after line which says: CARGS+=-DBINDIR=\"$(BINDIR)\"
                  # add:  CARGS+=-DSBINDIR=\"$(SBINDIR)\"
make utils
ln -s /opt/mohawk/lib/libphoenix.so.2.2.2 /lib/
/opt/mohawk/sbin/mcache &

In your php.ini, add:   
[Session]
; Use mcache as the save handler
session.save_handler = mcache
; Set the host which runs the mcache daemon
session.save_path = localhost

Let us test if mcache server is running:

/opt/mohawk/bin/mping
You should see:
Usage: /opt/mohawk/bin/mping host
Pings a session daemon
Using localhost
localhost:8086 is alive

Great! You mcache server is now up and running and listening for connections.

You can add above command to your start up scripts so server will run next time you reboot.  Easiest way to achieve this is to add that command to end of /etc/rc.local

32 bit installation is now complete! 

———————

I could not get 64 bit install to go but here are my notes for whoever wants to try it.  If you get it working, please come back and comment on how you got it installed.

64 bit install notes:First error:  CPU you selected does not support x86-64 instruction set
to fix this, edit config/unixgcc.mak and remove all instances of -mtune=pentium3

Following are code changes to fix some other errors:

line 83 in phmalloc.h
virtual void *memdup(void *mem, unsigned int cb);
to
virtual void *memdup(void *mem, size_t cb);

line 446 in mexpat.cpp
static void *xmlalloc(void *context, unsigned int cb)
to
static void *xmlalloc(void *context, size_t cb)

static void *xmlrealloc(void *context, void *p, unsigned int cb)
to
static void *xmlrealloc(void *context, void *p, size_t cb)

NOTE: This set up is very “open” and should not be used on servers which are facing the world. This is for private network where you trust all the computers and its users.

Installing Samba (using yum on CentOS and Fedora): yum install samba
Installing Samba (using rpm):

1. Obtain Samba rpm from rhn.redhat.com
2. rpm -ivh samba*.rpm

Configuring Samba:
cd /etc/samba
mv smb.conf smb.conf.backup
vi smb.conf

Paste content below in to your vi:

[global]
workgroup = wrkgrp
netbios name = smbserver
security = SHARE
load printers = No
default service = global
path = /home
available = No
encrypt passwords = yes
[share]
writeable = yes
admin users = smbuser
path = /home/share
force user = root
valid users = smbuser
public = yes
available = yes

save and exit

adduser smbuser #add unix account
passwd smbuser #set unix account password
smbpasswd -a smbuser #lets create same user account on samba
<put same password as your unix account password>
/etc/init.d/smb restart

Now let us setup drive letter on our Windows so we can easily access these files.

Start -> run -> cmd <enter>

At the prompt type: net use z: \\ip_of_your_samba_server\share /user: smbuser password_you_assigned

That is it! At this point you have successfully set up Samba under Linux and are now successfully connected to your share from your Windows machine.

You can test to see if you have LWP installed by typing:
perl -MLWP -le "print(LWP->VERSION)"
If you get something like: Can’t locate LWP.pm in @INC means that you don’t have it installed. To install LWP, type:
perl -MCPAN -eshell
NOTE: most times it is okey for you to accept default answers to questions cpan asks.
You can read through cpan help by typing “h” without the quotes at cpan> prompt.
To continue installing LWP, type:
install Bundle::LWP
After few questions, and some text scrolling, you will have LWP installed. If for some reason you don’t want to do it this way, you can always obtain source for the module you are trying to install and build it from source files. You can obtain these files from CPAN site

10.0.0.2:/export/files /files intr

After that I tested the setting by typing: mount /files Everything worked as expected and files was mounted successfully. At this point I wanted to make sure server will do nfs mounts automatically at boot up. To my surprise once I rebooted the server, nfs mount did not happen. I checked the logs and found this:

May 11 11:00:24 www3 mount: mount: mount to NFS server '10.0.0.2' failed:
May 11 11:00:24 www3 mount: System Error: No route to host.

But once server booted up, I typed mount /files and again, mount worked great. After poking around for a while I found out that when netfs script runs, netfs can not find network routes (due to network is still initializing). I tried few ways to get around this issue and settled on following solution:

vi /etc/init.d/netfs
insert: action $”Sleeping for 30 secs: ” sleep 30
right after: [ ! -f /var/lock/subsys/portmap ] && service portmap start
and right before: action $”Mounting NFS filesystems: ” mount -a -t nfs,nfs4

Basically we are going to give enough time for network to start and set up routes etc. You can play with that number after sleep command (we are basically pausing netfs script execution for 30 secs) and see what works for you. Once you are done, save/exit and reboot the server to see if number you used is sufficient sleep time. You can type df -h to see if it was mounted. If it wasn’t mounted, you can check /var/log/messages to see if nic was starting after nfs mount. If it is after, you will have to increase that number after sleep. Remember that you are only pausing the netfs script execution. Rest of the system continues to boot up. After I made changes, I checked my df output after reboot and my mount was there. I also checked /var/log/messages to see if everything looks ok there:

May 11 11:22:14 www3 kernel: bnx2: eth0 NIC Link is Up, 1000 Mbps full duplex
May 11 11:22:16 www3 netfs: Sleeping for 30 secs: succeeded
May 11 11:22:17 www3 netfs: Mounting NFS filesystems: succeeded