Linux and Oracle and Hiu

The hint of extracting tarball

2009-09-09T19:42:00.000-07:00

I created a directory called, file. Then, i touched 3 dummy files, file1, file2, file3.

[root@rhel54-1 file]# ls
file1 file2 file3

when i zip those file. I choose two different ways, one with gzip compression and one without

[root@rhel54-1 ~]# tar -cvf file.tar.gz file/
file/
file/file2
file/file3
file/file1

[root@rhel54-1 ~]# tar -zcvf file.tgz file
file/
file/file2
file/file3
file/file1

[root@rhel54-1 ~]# tar -jcvf file.tar file
file/
file/file2
file/file3
file/file1

I have three tarball files right now. Then, I do a file command on my tarballs file

[root@rhel54-1 ~]# file file.tar.gz
file.tar.gz: POSIX tar archive

[root@rhel54-1 ~]# file file.tgz
file.tgz: gzip compressed data, from Unix, last modified: Thu Sep 10 10:27:48 2009

[root@rhel54-1 ~]# file file.tar
file.tar: bzip2 compressed data, block size = 900k

Cool. I have three different formats. POSIX tar archive, and gzip and bzip2 file.

So, when i extract the tarballs. i will prompt in the command.
1. tar -zvxf for gzip tarball
2. tar -xvf for POSIX tar archive
3. tar -jvxf for bzip2 tarball

Obviously, the size of those tarballs also varying.

[root@rhel54-1 ~]# ls -sh file.*
4.0K file.tar 12K file.tar.gz 4.0K file.tgz

gzip and bzip2 is much more better than POSIX tarball.

love tai ji

2009-06-11T21:30:00.000-07:00

RPM packaging

2009-06-09T18:17:00.000-07:00

NUM_RPM_INSTANCE == 1 is a normal installation

NUM_RPM_INSTANCE == 2 is a normal upgrading

NUM_RPM_INSTANCE == 0 is a normal uninstallation

Here are the actual values passed during an install:

Run %pre of new package (1)
Install new files
Run %post of new package (1)

Here are the values passed during an upgrade:

Run %pre of new package (2)
Install new files
Run %post of new package (2)
Run %preun of old package (1)
Delete any old files not overwritten by newer ones
Run %postun of old package (1)

Here are the values passed during a delete:

Run %preun of old package (0)
Delete files
Run %postun of old package (0)

Getting GREP on some colors

2009-06-01T19:44:00.000-07:00

export GREP_COLOR='1;32'

Regexp lesson 2

2009-05-11T23:04:00.000-07:00

Regular expression lesson 2 [ and ] is a define a character set, everything between them is part of the set, and any one of the set members must match (but not all).

Multiple ranges may be combined in a single set. For example, the following pattern matches any alphanumeric character in uppercase or lowercase, but not anything that is neither a digit nor an alphabetic character:

[A-Za-z0-9]

This pattern is shorthand for

[ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234567890]

TEXT
abbreviated as RegEx or regex

REGEXP
[Rr]eg[Ee]x

RESULT
abbreviated as RegEx or regex

Regexp lesson 1

2009-05-11T22:52:00.000-07:00

Regular expression lesson 1 . matches any character. \is used to escape characters and to start special character sequences.

TEXT

sales1.xls

orders3.xls

sales2.xls

sales3.xls

apac1.xls

europe2.xls

na1.xls

na2.xls

sa1.xls

REGEXP

.a.\.xls

RESULT

sales1.xls

orders3.xls

sales2.xls

sales3.xls

apac1.xls

europe2.xls

na1.xls

na2.xls

sa1.xls


TEXT
sales1.xls

orders3.xls

sales2.xls

sales3.xls

apac1.xls

europe2.xls

na1.xls

na2.xls

sa1.xls

ca1.xls


REGEXP
[ns]a.\.xls


RESULT
sales1.xls

orders3.xls

sales2.xls

sales3.xls

apac1.xls

europe2.xls

na1.xls

na2.xls

sa1.xls

ca1.xls

Highlighting matching on regexp

2009-05-11T22:46:00.000-07:00

hi all,

If you wish to declare a environment variable to have regular expression operates with grep where the standard output showing the colors, in fact, you can!

export GREP_OPTIONS='--color=auto'

Have fun.

yen_onn_hiu@nasilemak:~/regexp> grep .a.. text1
sales1.xls
sales2.xls
sales3.xls
apac1.xls
na1.xls
na2.xls
sa1.xls

VAS troubleshooting skills

2009-05-07T20:05:00.000-07:00

Yesterday, I have been spending times to debug the vastool. That's give me error when prompting the id of the account.

End up, I did a "vas merge" to get all the vas cache load into the /etc/passwd and /etc/group. That's pain. But, It works temporarily.

Here are the bunch of vas command for troubleshooting.

1. To check on the user access

vastool user checkaccess [account_name]

2. To get the vastool status result

ftp://ftp.vintela.com/vas/support/vas_status.sh.gz

To get the vastool snapshot

/opt/quest/libexec/vas/scripts/vas_snapshot.sh

3. To flush the cache

vastool flush

4. To check is vas

vastool isvas user [account name]

5. Test AD connection and user password
vastool kinit [account_name]

6. Test VAS service access control (assuming your using sshd)
vastool user checkaccess -s sshd [acount_name]

7. Check authentication logs
1) Add the words "debug" and "trace" to the end of all pam_vas lines in /etc/pam.d/system-auth
2) Add "*.debug /var/log/debug" to /etc/syslog.conf
3) Restart syslog daemon
4) Attempt login
5) Look at output in /var/log/debug for indication/reason of failure

8. You can also turn on vasd debug if desired
1) vastool configure vas vasd debug-level 3

vmware way of discovering lun

2009-03-03T01:29:00.000-08:00

In order to list a vmware lun, please do this.

[root@testdev01 volumes]# esxcfg-mpath -l
Disk vmhba1:0:16 /dev/sdr (204800MB) has 4 paths and policy of Most Recently Used FC 10:0.0 10000000c9610905<->5006016941e02f2b vmhba1:0:16 Standby FC 10:0.0 10000000c9610905<->5006016141e02f2b vmhba1:1:16 On active FC 14:0.0 10000000c96106fc<->5006016041e02f2b vmhba2:0:16 On FC 14:0.0 10000000c96106fc<->5006016841e02f2b vmhba2:1:16 Standby preferred

Disk vmhba1:0:17 /dev/sds (204800MB) has 4 paths and policy of Most Recently Used FC 10:0.0 10000000c9610905<->5006016941e02f2b vmhba1:0:17 Standby FC 10:0.0 10000000c9610905<->5006016141e02f2b vmhba1:1:17 On active FC 14:0.0 10000000c96106fc<->5006016041e02f2b vmhba2:0:17 On FC 14:0.0 10000000c96106fc<->5006016841e02f2b vmhba2:1:17 Standby preferred

Disk vmhba1:0:18 /dev/sdt (204800MB) has 4 paths and policy of Most Recently Used FC 10:0.0 10000000c9610905<->5006016941e02f2b vmhba1:0:18 Standby FC 10:0.0 10000000c9610905<->5006016141e02f2b vmhba1:1:18 On active FC 14:0.0 10000000c96106fc<->5006016041e02f2b vmhba2:0:18 On FC 14:0.0 10000000c96106fc<->5006016841e02f2b vmhba2:1:18 Standby preferred

Discovering HBA information from RHEL3 and SLES10

2009-02-10T22:10:00.000-08:00

If you wish to retrieve information on HBAs on RHEL3 or SLES10 SP1. Basically, here is the path that you are looking for.

RHEL3: /proc/scsi/lpfc/
SLES10 SP1: /sys/class/fc_host/

As for the SLES10 SP2 : /sys/class/scsi_host/

There are bunch of information like HBA model, firmware, speed, port_state and WWN.

Discovering HBA from OEL5

2009-02-10T21:57:00.000-08:00

hbanyware prepares a good place to query the hba information.

e.g.
[root@test03 audit]# /usr/sbin/hbanyware/hbacmd listhbas
Manageable HBA List
Port WWN : 10:00:00:00:c9:63:1d:79
Node WWN : 20:00:00:00:c9:63:1d:79
Fabric Name: 10:00:00:05:1e:04:6c:8b
Flags : 8000f0e5
Host Name : test03.hiu.com
Mfg : Emulex Corporation
Port WWN : 10:00:00:00:c9:63:1d:34
Node WWN : 20:00:00:00:c9:63:1d:34
Fabric Name: 10:00:00:05:1e:04:3f:9d
Flags : 8000f0e5
Host Name : test03.hiu.com
Mfg : Emulex Corporation

In order to get the HBA Model, you can get the information from hbanyware command as well.

[root@test03 audit]# /usr/sbin/hbanyware/hbacmd hbaAttributes 10:00:00:00:c9:63:1d:79
HBA Attributes for 10:00:00:00:c9:63:1d:79
Host Name : test03.hiu.com
Manufacturer : Emulex Corporation
Serial Number : BG72036851
Model : LPe1150-E
Model Desc : EMC LPe1150-E 4Gb PCIe Fibre Channel Adapter
Node WWN : 20 00 00 00 c9 63 1d 79
Node Symname : Emulex LPe1150-E FV2.72A2 DV8.2.0.22
HW Version : 2057706d
Opt ROM Version:
FW Version : 2.72A2 (W3F2.72A2), sli-3
Vendor Spec ID : 10DFNumber of Ports: 1
Driver Name : lpfc
Device ID : F0E5
HBA Type : LPe1150-E
Operational FW : SLI-3 Overlay
SLI1 FW : SLI-1 Overlay 2.72a2
SLI2 FW : SLI-2 Overlay 2.72a2
SLI3 FW : SLI-3 Overlay 2.72a2
IEEE Address : 00 00 c9 63 1d 79
Boot BIOS : 1.70a3
Driver Version : 8.2.0.22; HBAAPI(I) v2.1.g, 12-07-07
Kernel Version : 1.20a4
HBA Temperature: Not Available

Configure opensuse11 + rewrite_module

2009-02-08T00:52:00.000-08:00

if you are using opensuse 11 with cakephp development, most likely you will need to have the rewrite_module enabled on apache2.

All apache2 modules are kept at /usr/lib/apache2. Please use this command to enable your rewrite_module. Enjoy!

a2enmod rewrite
/etc/init.d/apache2 force-reload

Passed Novell CLP10

2008-10-12T20:44:00.000-07:00

After making my mind to go for the certification, i finally passed the cert. It is not that too hard but, the remote connection is slow and lame. What make worse of it is the timer is keep on triggering, making the feeling of panics and nervous.

Backup Files

2008-10-08T19:55:00.000-07:00

TAR
We have two different backup, full backup and incremental backup.

Let's pick our backup folder as /srv/www/htdocs.

To do a full backup, you need to prompt this command

cd /srv/www
tar cvz -g /tmp/backup/snapshot_htdocs -f /tmp/backup/htdocs_full.tar.gz htdocs

To do a incremental backup.

tar cvz -g /tmp/backup/snapshot_htdocs -f /tmp/backup/htdocs_incremental.tar.gz htdocs

RSYNC
Rsync backup is much more better than tar. Both incremental and full backup can use the same command to execute. Rsync will pick the changes on backup target without capturing the file snapshot.

rsync -ave ssh root@ip_addr_to_be_backup:/home/users /tmp/backup_dir

syslog

2008-10-06T20:13:00.000-07:00

The configuration of syslog-ng is distributed across three files

/etc/sysconfig/syslog
/etc/syslog-ng/syslog-ng.conf.in
/etc/syslog-ng/syslog-ng.conf

/etc/sysconfig/syslog contains general parameters applicable to syslog-ng.

/etc/syslog-ng/syslog-ng.conf.in is the template used to create the configuration file /etc/syslog-ng/syslog-ng.conf, which is the configuration file actually used by syslog-ng. both files have the same syntax.

syslogd and syslog-ng share two concepts that you have to understand to the able to configure either one:

facilities
priorities

Creating a virtual interface on opensuse11

2008-10-05T21:15:00.001-07:00

a normal network interface can be queried via the command ifconfig

opensuse01:~ # ifconfig

eth2 Link encap:Ethernet HWaddr 00:0C:29:4F:74:C5

inet addr:192.168.80.134 Bcast:192.168.80.255 Mask:255.255.255.0

inet6 addr: fe80::20c:29ff:fe4f:74c5/64 Scope:Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:346 errors:0 dropped:0 overruns:0 frame:0

TX packets:781 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:44214 (43.1 Kb) TX bytes:109649 (107.0 Kb)

Interrupt:18 Base address:0x2024

lo Link encap:Local Loopback

inet addr:127.0.0.1 Mask:255.0.0.0

inet6 addr: ::1/128 Scope:Host

UP LOOPBACK RUNNING MTU:16436 Metric:1

RX packets:326 errors:0 dropped:0 overruns:0 frame:0

TX packets:326 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:0

RX bytes:45674 (44.6 Kb) TX bytes:45674 (44.6 Kb)

============================================

To add the virtual interface.

ip addr add 192.168.80.135/24 brd + dev eth2 label eth2:1

ifconfig again to the command prompt will display this

eth2:1 Link encap:Ethernet HWaddr 00:0C:29:4F:74:C5

inet addr:192.168.80.135 Bcast:192.168.80.255 Mask:255.255.255.0

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

Interrupt:18 Base address:0x2024

============================================

Please do a ping to the new virtual interface.

opensuse01:~ # ping 192.168.80.135

PING 192.168.80.135 (192.168.80.135) 56(84) bytes of data.

64 bytes from 192.168.80.135: icmp_seq=1 ttl=64 time=0.034 ms

64 bytes from 192.168.80.135: icmp_seq=2 ttl=64 time=0.039 ms

64 bytes from 192.168.80.135: icmp_seq=3 ttl=64 time=0.049 ms

64 bytes from 192.168.80.135: icmp_seq=4 ttl=64 time=0.049 ms

Linux Users and Groups

2008-09-21T19:30:00.000-07:00

Linux stores all users and groups configuration data in the following files.

/etc/passwd
/etc/shadow
/etc/group

E.G

geeko:x:1000:100:Geeko Chameleon:/home/geeko:/bin/bash
geeko:$sdfsdf$123$asf234sdfasdf23132:13181:0:9999:7:-1::

The above illustration shows the entry for the user geeko with an encrypted password. Some users such as wwwrun or bin ave an * in the password field. This means that these users can not log in to the system, but are for special applications.

Command to manage the users and groups.

useradd -m : automatically generates the home directory for the user. Without this argument, the directory is created under /home/
useradd -c : creating a new user with the ext for comment field.
useradd -u : specifying the UID of the new account.
useradd -g : specifying the primary group of the user.
useradd -e : set the expire date.
usermod : used to modify the setting. All the options used by usermod is the same as useradd
passwd -l : a user can be locked out.
passwd -u : a user can be unlocked, or re-activated.
if /etc/shadow lists a user account where is the password field is started with !, it means this account had been locked.
passwd -S : list the status of a user account.
passwd -i : disable an account after the password has been expired for number of days
passwd -n : sets the minimum number of days before a password can be changed.
passwd -w : warns the user that in number of days his password will expire.
passwd -x : sets the maximum number of days a password remains valid. After number of days the password must be changed.

E.G passwd -x 30 -w 5 geeko

When the passwd command is used, the /etc/default/passwd file is checked for the encryption method.

Manage groups from the command line.

groupadd -g 200 sports : adding a new group, called sport with gid, 200
groupdel sports : deleting a group called sports
groupmod -g 201 sports : modifying the gid of sports group to 201
groupmod -A geeko : add the user geekp to the group
gpasswd : Change password for group accounts.

The standrad configuration information is derived from 2 importants files.

/etc/default/useradd
/etc/login.defs

Apache on SLES10

2008-09-14T21:00:00.000-07:00

To setup a basic apache webserver, you need to install

apache2
apache2-prefork
apache2-example-pages (optional)

Commands to administer apache2

To start apache2: rcapache2 start
To stop: rcapache2 stop
To let apache starts at boot time: insserv apache2
To reload the config file: rcapache2 reload
To restart daemon: rcapache2 restart
To examine the syntax of the config files: apache2ctl configtest
The default directory: /srv/www/htdocs. It is called DocumentRoot of the web server.
wwwrun is the user that executing apache2

Apache2 configuration files

/etc/apache2/httpd.conf - The main apache configuration file.
/etc/apache2/default-server.conf - Contains the basic web server setup. All options set in this file can be overwritten by other configuration files.
/etc/apache2/vhost.d - The directory for virtual host setups.
/etc/apache2/uuid - Sets the user and group id for apache. By default, apache uses wwwrun(uid) and www(gid)
/etc/apache2/server-tuning.conf - tune the performance of apache2.
/etc/apache2/errors.conf - configure the behavior of apache when a request cannot be performed.
/etc/apache2/ssl-global.conf - configure the connection encryption with SSL.

Create RSA Key Pair

cat /dev/random > /tmp/random Stop this command after a few seconds by pressing Ctrl-C
To create the server key: openssl genrsa -des3 -rand /tmp/random 1024 -out server.key
Sign the public key to create a certification: openssl req -new -x509 -key server.key -out server.crt
Copy the server.key to /etc/apache2/ssl.key/* and copy the server.crt to /etc/apache2/ssl.crt/*
To configure the main server, you need to add the following lines to /etc/apache2/default-server.conf
SSLEngine on
SSLCertificateFile /etc/apache2/ssl.crt/server.crt
SSLCertificateKeyFile /etc/apache2/ssl.key/server.key
APACHE_START_TIMEOUT="10" - This setting extends the start timeout of apache so that have more time to enter the passphrase of the private RSA key.
APACHE_SERVER_FLAGS="SSL" - This enables some directives that are necessary for SSL encrytion. It lets apache listen on port 443 instead of only to port 80.

Xen on SLES10

2008-09-14T19:42:00.000-07:00

Xen consists of two major components.

Virtual Machine Monitor (VMM) - A layer between physical hardware and VM. In general term, this is called hypervisor.
Xen Tools - a set of command line application used to administer VM.

VMM must be loaded before any of VMs are started. VM in xen are called as domains. Privileged domain, called domain0 is an interface to communicate directly with an adminstrator to access the physical hardware of the host machine.

An unprivileged domain is called domainU. To install Xen, the following package is needed.

xen
xen-tools
kernel-xen
xen-doc* (optional)

After the installation, the reboot is required to boot into Xen bootloader. In case the system is not booting properly, you can switch back to the non-virtualized system and disable the firewall.

rcSuSEfirewall2 stop
insserv -r SuSEfirewall2_setup
insserv -r SuSEfirewall2_init
insserv -r SuSEfirewall_final (conditional)

To manage Xen domains at the commands line.

Xen configuration file is located at: /etc/xen/vm
There are examples of template configuration file for a single domain: /etc/xen/examples
xm is the administration tools, it communicates with the xend management processes running on domain0 linux installation.
To start a vm, the create command is used: xm create -c -f /data/xen/SLES10-WebServer.conf
To list the currently running Xen domains: xm list
The list command contains the following fields: name, domid, memory, vcpus, state (r - running, b - blocked, domain has been created, but it is blocked when a domain is waiting for IO or nothing to do, p - pause, s - shutdown, c - crashed)
To connects you with the terminal of running domain: xm console domain_id
To disconnect from a terminal: use the keystrokes: Ctrl-]
To interrupt the execution a domain temporarily: xm pause domain_id
To unpause: xm unpause domain_id
To shutdown: xm shutdown domain_id
To force shutdown a not responding domain: xm destroy domain_id
To save the state of a domain for a longer time: xm save domain_id
To restore a domain from a resulting file: xm restore filename
To change the memory allocation for a domain: xm mem-set domain_id amount_of_memory_in_megabytes

Automate Domain Startup and shutdown

SLES10 comes with a start script called, xendomains, which included in the xen-tools package.
If domain0 is booted, all the domains with the configuration files located under /etc/xen/auto will be started.
If domain0 is shutdown, or rebooted, all the running Xen domains will be shutdown.
The script can be adjusted /etc/sysconfig/xendomains for some configuration options like: XENDOMAINS_MIGRATE. It will migrate domain automatically to a different host when a domain0 is shutdown. The flags has to be set to the IP address of the target machine.

Understand Xen Networking

domain0 is controlling the physical network interfaces of the host system. Unprivileged domains are connected to domain0 through Virtual Ethernet adapters.
domainU (VE) <---->(VE)domain0(Physical Ethernet)<------>Network(LAN)
The default mechanism to connect VE and PE in domain0 is bridging.
When a new domain is created, the following steps happened.
1. Xen provides a VE to the new domain
2. xend creates a new VE in domain0
3. both VE are connected through a virtual point to point connection.
4. The VE in domain0 is added to the bridge with the physical interface.
xend performs the networking changes with the help of scripts: /etc/xen/scripts.
The script to initiate the bridge xenbr0: /etc/xen/scripts/nework-bridge
The script to start and add the VE: /etc/xen/scripts/vif-bridge
To configure the network scripts are used by xend: /etc/xen/xend-config.sxp
Command: ip a is prompted on domain0 will list down all the different interface naming schema.
1. peth - physical interfaces in domain0. peth devices are connected to the network bridge
2. vif - virtual interfaces which are part of the bridge. E.g: vif6.0 is connected to the first vif in domain 6.
3. veth - virtual interfaces are connected to the vif interfaces of domain0 (vif0.x)
4. eth0 - the default veth interface is named eth0 and connected with vif0.0. This is the default network interface of domain0.
5. xenbr0 - the default bridge that connects virtual and physical interfaces.

Migrate a Guest Domain

2 methods: Use domain save and restore or Use migration and live migration.
Domain Save and Restore
1. suspend the domain: xm save domain_id filename
2. copy the file to the new host system, then restore the domain: xm restore filename
Migration and Live Migration
1. xm migrate domain_id target_host
2. By adding --live migration flag, the downtime during the migration can be reduced.
3. /etc/xen/xend-config.sxp with 2 importants flags: xend-relocation-server yes, xend-relocation-hosts-allow '^localhost$'

VI Cursor Movement Commands

2008-09-03T20:29:00.000-07:00

xargs and find

2008-08-30T01:33:00.000-07:00

xargs and find

find and xargs do go very well together: find to locate what you're looking for, and xargs to run the same command on each of the things found.

Traditionally, an advantage to xargs was its ability to handle long command lines before failing, unlike some other commands. This command:

rm `find tmp -maxdepth 1 -name '*.mp3'`

is intended to remove all tmp/*.mp3 files (and ignore any subdirectories), but can fail with an "Argument list too long" message. This exact equivalent:

find tmp -maxdepth 1 -name '*.mp3' -maxdepth 1 | xargs rm

does exactly the same thing but will avoid the problem by batching arguments up. More modern kernels (since 2.6.23) shouldn't have this issue, but it's wise to make your scripts as portable as possible; and the xargs version is also easier on the eye.

You can also manually batch arguments if needed, using the -n option.

find tmp -maxdepth 1 -name '*.mp3' -maxdepth 1 | xargs -n1 rm

will pass one argument at a time to rm. This is also useful if you're using the -p option as you can confirm one file at a time rather than all at once.

Filenames containing whitespace can also cause problems; xargs and find can deal with this, using GNU extensions to both to break on the null character rather than on whitespace:

find tmp -maxdepth 1 -name *.mp3 -print0 | xargs -0 rm

You must use these options either on both find and xargs or on neither, or you'll get odd results.

Another common use of xargs with find is to combine it with grep. For example,

find . -name '*.pl' | xargs grep -L '^use strict'

will search all the *.pl files in the current directory and subdirectories, and print the names of any that don't have a line starting with 'use strict'. Enforce good practice in your scripting!

Configure Special File Permissions

2008-08-21T00:51:00.000-07:00

Name: sticky bit, 1, t
Users can only delete files when they are owner, or when they are root or owner of the directory. This is usually applied to be /tmp directory.

Name: SGID (Set GroupID), 2, s
When a program is run, this sets the group ID of the process to that of the group of the file. Files created in this directory belong to the group to which the directory belongs and not the primary group of the users. New directories created in this directories inherit the SGID bit.

Name: SUID (Set UserID), 4, s
Sets the user ID of the process to that of the owner of the file when the program is run.

UUID

2008-08-20T18:14:00.001-07:00

1. If you don't know the UUID of your disk, you can find it by using one of the several commands below:

host # vol_id /dev/sda3
...
ID_FS_UUID=a1331d73-d640-4bac-97b4-cf33a375ae5b
...

or:

host # blkid /dev/sda3 <-- Leave blank to show all disks
/dev/sda3: LABEL="/" UUID="a1331d73-d640-4bac-97b4-cf33a375ae5b" SEC_TYPE="ext3" TYPE="ext2"

also:

host # ls -l /dev/disk/by-uuid|grep sda3
lrwxrwxrwx 1 root root 10 11. Okt 18:02 a1331d73-d640-4bac-97b4-cf33a375ae5b-> ../../sda3

2. If you prefer to generate your own UUID's (see above), you can use the uuidgen command and couple it with tune2fs to change the default UUID assigned to your disk by the system, like this:

host # uuidgen
1d721189-7b71-4315-95a7-1c3abc90d379
host # tune2fs -U 1d721189-7b71-4315-95a7-1c3abc90d379 /dev/sda3

3. Then again, if you already know the UUID, you might want to find out what disk it's associated with. You can generally get this information with the "findfs" command, like so:

host # findfs UUID=a1331d73-d640-4bac-97b4-cf33a375ae5b
/dev/sda3

Of course, using some of the commands above and grepping out part of the UUID will also get you your answer, like:

host # ls -l /dev/disk/by-uuid|grep a1331d73-d640-4bac-97b4-cf33a375ae5b
lrwxrwxrwx 1 root root 10 11. Okt 18:02 a1331d73-d640-4bac-97b4-cf33a375ae5b-> ../../sda3

or

host # blkid|grep a1331d73-d640-4bac-97b4-cf33a375ae5b <-- remember that blkid with no arguments returns all of the system disk
/dev/sda3: LABEL="/" UUID="a1331d73-d640-4bac-97b4-cf33a375ae5b" SEC_TYPE="ext3" TYPE="ext2"

4. And, lastly (for this post, at least ;), you can mount your disks using the UUID, and even incorporate that automated UUID mounting into your /etc/fstab. To mount directly from the command line, you can do something like this:

host # mount -U a1331d73-d640-4bac-97b4-cf33a375ae5b /directory/you/mount/this/disk/on

and you could instruct your system to mount this partition by UUID from within the fstab, as well. It works basically the same way that the LABEL keyword does:

host # cat /etc/fstab
...
UUID=a1331d73-d640-4bac-97b4-cf33a375ae5b /directory/you/mount/this/disk/on ext3fs defaults 1 1

And, at this point, you should be able to figure your way around using UUID's to manipulate your disk on Linux with no problem. Enjoy, and please "be careful" :)

Expect and SSH

2008-05-15T08:12:00.000-07:00

#!/usr/bin/expect -f

set username [lrange $argv 0 0]
set password [lrange $argv 1 1]
set ipaddr [lrange $argv 2 2]
set timeout -1

spawn ssh $username@$ipaddr
match_max 100000

expect {
"*?(yes/no)*" { send -- "yes\r" }
"*?assword:*" { send -- "$password\r" }
}

set timeout 10
expect {
"*?assword:*" { send -- "$password\r" }
}

expect "$username*" { send -- "sudo su - \r" }
interact

System Global Area

2008-04-27T07:25:00.000-07:00

The SGA consists of several memory structures:
1. Shared Pool
2. Database Buffer Cache
3. Redo Log Buffer
4. Other structures (for example, lock and latch management, statistical data)

Shared Pool
It consists of two key performance-related memory structures, Library Cache, Data Dictionary Cache. Because the Shared Pool can be shared globally, such as reusable SQL execution plans, PL/SQL packages, procedures, functions, and cursor information, it must be sized to accommodate the needs of both the fixed and variables areas. Memory allocation for the Shared Pool is determined by the SHARED_POOL_SIZE initialization parameter. It can be dynamically resized using ALTER SYSTEM SET. After performance analysis, this can be adjusted but the total SGA size cannot exceed SGA_MAX_SIZE.

Libray Cache
It stores information about eh most recently used SQL and PL/SQL statements. It enables the sharing of commonly used statements which is managed by the least recently used (LRU) algorithm.

Data Dictionary Cache
This is a collection of the most recently used definitions in the database, which includes information about database files, tables, indexes, columns, users, privileges, and other database objects. During the parse phase, the server process looks at the data dictionary for information to resolve object names and validate access. By caching data dctionary information into memory improves response time on queries and DML.

There are two additional memory structures that can be configured within the SGA:
1. Large Pool
2. Java Pool

Oracle Architecture Diagram

2008-04-23T12:13:00.000-07:00

Oracle Primary Components

2008-04-23T11:21:00.000-07:00

Oracle server:
There are several files, processes and memory structures in an Oracle server, however, not all of them are used when processing a SQL statement. Some are used to improve the performance of the databse, to ensure that the database can be recovered in the event of a software of hardware error, ot to perform other tasks necessary to maintain the database. The Oracle server consists of an Oracle instance and an Oracle database

Oracle Instance:
An Oracle instance is the combination of the background processes and memory structures. The instance must be started to access the data in the database. Every time an instance is started, a System Global Area (SGA) is allocated and Oracle background processes are started. Background processes perform functions on behalf of the invoking procceses. They consolidate functions that would otherwise be handled my multiple Oracle programs running for each user. The background processes perform input/output (I/O) and monitor other ORacle processes to provide increased parallelism for better performance and reliability. An Oracle instance consists of the System Global Area (SGA) memory structure and the background processes that are used to manage a database. An instance is identified by using methods specific to each operating system. The instance can open and use only one database at a time.

Oracle Database:
The general purpose of a database is to store and retrieve related information. an Oracle database has a logical and a physical structure. The physical structure of the database is a set of operating system files in the database. An Oracle database consists of three file types.
1. Data files containing the actual data in the database.
2. Online redo log files containing a record of changes made to the database to enable recovery of the data in case of failures.
3. Control files containing information necessary to maintain and verify database integrity.

Memory Structure
Oracle's memory structure consists of two memory areas known as
1. System Global Area (SGA): Allocated at instance startup, and is a fundamental component of an Oracle instance.
2. Program Global Area (PGA): Allocated when the server process is started.

Migration ASM from /dev/sdc to /dev/sdb

2008-01-09T06:35:00.000-08:00

1. Startup ASM on sdc
[root@oracle01 ~]# fdisk -l /dev/sdc

Disk /dev/sdc: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdc1 1 487 3911796 83 Linux
/dev/sdc2 488 974 3911827+ 83 Linux
[root@oracle01 ~]# su - oracle
[oracle@oracle01.myserver.com /home/oracle]
$ export ORACLE_SID=+ASM
[oracle@oracle01.myserver.com /home/oracle]
$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Wed Jan 9 22:10:09 2008

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to an idle instance.

SQL> startup mount
ASM instance started

Total System Global Area 83886080 bytes
Fixed Size 1217836 bytes
Variable Size 57502420 bytes
ASM Cache 25165824 bytes
ASM diskgroups mounted
SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
[oracle@oracle01.myserver.com /home/oracle]
$ asmcmd
ASMCMD> lsdg
State Type Rebal Unbal Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Name
MOUNTED NORMAL N N 512 4096 1048576 7640 5284 0 2642 0 DATA/
ASMCMD> exit

2. Create filesystem onto sdb and do a dd sdc[1-2] to files (data_lun1, data_lun2)

[root@oracle01 ~]# fdisk -l /dev/sdb

Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 1305 10482381 83 Linux
[root@oracle01 ~]# mkfs /dev/sdb1
mke2fs 1.35 (28-Feb-2004)
max_blocks 2683489280, rsv_groups = 81894, rsv_gdb = 639
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
1310720 inodes, 2620595 blocks
131029 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2684354560
80 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Writing inode tables: done
inode.i_blocks = 46016, i_size = 4243456
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 33 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@oracle01 ~]# mount /dev/sdb1 /mydata/
[root@oracle01 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
7.3G 3.5G 3.5G 51% /
/dev/sda1 99M 9.0M 85M 10% /boot
none 126M 0 126M 0% /dev/shm
/dev/sdb1 9.9G 23M 9.4G 1% /mydata
[root@oracle01 ~]# dd if=/dev/sdc1 of=/mydata/data_lun1 bs=1M
3820+1 records in
3820+1 records out
[root@oracle01 ~]# dd if=/dev/sdc2 of=/mydata/data_lun2 bs=1M
3820+1 records in
3820+1 records out

3. Shutdown ASM

[root@oracle01 ~]# su - oracle
[oracle@oracle01.myserver.com /home/oracle]
$ export ORACLE_SID=+ASM
[oracle@oracle01.myserver.com /home/oracle]
$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Wed Jan 9 22:20:36 2008

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options

SQL> shutdown immediate
ASM diskgroups dismounted
ASM instance shutdown

4. Delete /dev/sdc1 and /dev/sdc2. Create a filesystem of 9.9G.

[root@oracle01 ~]# fdisk /dev/sdc

The number of cylinders for this disk is set to 1305.
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): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4):
Value out of range.
Partition number (1-4): 1
First cylinder (1-1305, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1305, default 1305): 1305

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@oracle01 ~]# partprobe
Warning: Unable to open /dev/hdc read-write (Read-only file system). /dev/hdc has been opened read-only.
[root@oracle01 ~]# mkfs /dev/sdc1
mke2fs 1.35 (28-Feb-2004)
max_blocks 2683489280, rsv_groups = 81894, rsv_gdb = 639
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
1310720 inodes, 2620595 blocks
131029 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2684354560
80 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Writing inode tables: done
inode.i_blocks = 46016, i_size = 4243456
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 24 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@oracle01 ~]# mkdir /mydata2
[root@oracle01 ~]# mount /dev/sdc1 /mydata2
[root@oracle01 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
7.3G 3.5G 3.5G 51% /
/dev/sda1 99M 9.0M 85M 10% /boot
none 126M 0 126M 0% /dev/shm
/dev/sdb1 9.9G 7.5G 1.9G 81% /mydata
/dev/sdc1 9.9G 23M 9.4G 1% /mydata2

5. Move data_lun[1-2] to this filesystem /mydata2

[root@oracle01 ~]# cp /mydata/* /mydata2/
cp: omitting directory `/mydata/lost+found'
[root@oracle01 ~]# cd /mydata2
[root@oracle01 mydata2]# ls -sh
total 7.5G
3.8G data_lun1 3.8G data_lun2 16K lost+found

6. Creating /dev/sdb[1-2]

[root@oracle01 mydata2]# fdisk /dev/sdb

The number of cylinders for this disk is set to 1305.
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/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 1305 10482381 83 Linux

Command (m for help): d
Selected partition 1

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1305, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1305, default 1305): 487

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (488-1305, default 488):
Using default value 488
Last cylinder or +size or +sizeM or +sizeK (488-1305, default 1305): 974

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

7. dd the data_lun[1-2] back to /dev/sdb[1-2]

[root@oracle01 mydata2]# fdisk -l /dev/sdb

Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 487 3911796 83 Linux
/dev/sdb2 488 974 3911827+ 83 Linux

[root@oracle01 mydata2]# dd if=/mydata2/data_lun1 of=/dev/sdb1 bs=1M
3820+1 records in
3820+1 records out
[root@oracle01 mydata2]# dd if=/mydata2/data_lun2 of=/dev/sdb2 bs=1M
3820+1 records in
3820+1 records out
[root@oracle01 asm]# ln -s /dev/sdb1 /u02/oradata/asm/data_lun1
[root@oracle01 asm]# ln -s /dev/sdb2 /u02/oradata/asm/data_lun2
[root@oracle01 asm]# chown -R oracle:oinstall /u02/oradata/asm/data_lun*
[root@oracle01 asm]# chmod -R 660 /u02/oradata/asm/data_lun*

8. Start and mount ASM on /dev/sdb[1-2]

[root@oracle01 asm]# su - oracle
[oracle@oracle01.myserver.com /home/oracle]
$ export ORACLE_SID=+ASM
[oracle@oracle01.myserver.com /home/oracle]
$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Wed Jan 9 22:58:11 2008

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to an idle instance.

SQL> startup mount
ASM instance started

Total System Global Area 83886080 bytes
Fixed Size 1217836 bytes
Variable Size 57502420 bytes
ASM Cache 25165824 bytes
ASM diskgroups mounted
SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
[oracle@oracle01.myserver.com /home/oracle]
$ asmcmd
ASMCMD> lsdg
State Type Rebal Unbal Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Name
MOUNTED NORMAL N N 512 4096 1048576 7640 5284 0 2642 0 DATA/
ASMCMD>

9. Start Database instance

[oracle@oracle01.myserver.com /home/oracle]
$ export ORACLE_SID=testdb
[oracle@oracle01.myserver.com /home/oracle]
$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Wed Jan 9 23:00:00 2008

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to an idle instance.

SQL> startup open
ORACLE instance started.

Total System Global Area 167772160 bytes
Fixed Size 1218316 bytes
Variable Size 71305460 bytes
Database Buffers 92274688 bytes
Redo Buffers 2973696 bytes
Database mounted.
Database opened.
SQL>

wget and bash

2007-12-04T20:10:00.000-08:00

If you want to download a script and run it right away, then, you can run this command to ease your task.

wget -qO- http://myserver/myscript.sh | /bin/bash

My First Posting

2007-11-13T06:17:00.000-08:00

Hi all,

I have been hearing my friends doing a lot of blogging from time to time. It attracted me so much when I knew that blogging can be a fun thing to do. So, I took my initiative to write my own blogging site.

I am a one of the Linux/Unix big fan. So much likely, I will write some articles about Linux related technologies and research.