Mesiols Day

What's going on in Mesiols work day

Wednesday, March 4, 2009

Extend logical volume on AIX 5.3

Today i extented an logical volume and filesystem on AIX 5.3

The following steps i had to do:

- create new LUN on storage
- run cfgmgr on target host to find new LUN as disk
- run smit and extend number of physical volumes for the logical volume
- run extendlv NAME_OF_LV SIZE_TO_EXTENT
+ here it was: "extendlv dbtest 20G" for new 20 gigabyte space
- run chfs -a size=+20480M to extend the filesystem
+ chfs requires 72 minutes to do the job, while there was no I/O on the filesystem

Saturday, February 28, 2009

Mapping windows key to Linux key of choice


i wanted to map the windows key on a Dell Inspirion to a useful Linux key on my son's notebook. This can be done the following way:

Use xev command to capture the key code. Left windows button should be key code 115.

Than you can do the following:

xmodmap "keycode 115 = F20"

This maps left windows button to function key 20.

To have the Windows key-mappings enabled automatically every time you start X either put the xmodmap commands in your ~/.xinitrc file or, preferably, create a file ~/.xmodmaprc and include the xmodmap options, one per line, then add the following line to your ~/.xinitrc:

xmodmap $HOME/.xmodmaprc

After that you can map the F20 inside your window manager to the function you like to use.

Thursday, February 26, 2009

rewrite all http to https in Apache


i had to do some web server configuration. Requirement was, that all http traffic should be redirected to https on the server.

I used mod_rewrite to do the job with the following configuration statement

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

Don't forget to configure SSL on the server :)

Wednesday, February 25, 2009

I deal with various storage management systems for years, but last week i found a tool completely new to me.

I had to manage a Linux cluster with several storages and the customer had installed a tool called EVMS, the opensource Enterprise Volume Management System. It provides nearly the same functionality as Veritas Enterprise Administrator and VxVM specific for Linux.

You'll get a intuitive GTK GUI, a ncurses based textmode UI and a commandline interface.

You'll try it? Take a look at EVMS Sourceforge Page.

new year and a lot of work to do.

Today i have found that after deleting a Linux software RAID partition there is always information stored about the RAID configuration on the disk.

To delete this information, i used

mdadm --manage --stop /dev/md0
mdadm --misc --zero-superblock /dev/sdb1

This solved my problem.

Wednesday, December 3, 2008

Get rid of ORA-04031 "cannot allocate XXXX Bytes ..."

Today a customer called telling me he was unable to use his software, because at login he receivces an
ORA-04031 "cannot allocate XXX Bytes ..."

First mind "aah out of shared pool".

First i tried an

But this doesn't solve the problem.

So i decided to dive into the database and take a look what's going on.

The following query determines the available memory for SHARED_POOL_SIZE in Oracle SGA

SQL> select sum (bytes)/1024/1024 from v$sgastat where pool=’shared pool’;

The above query provides the shared pool size in mega bytes.

The following query determines the total used memory by shared_pool in Oracle SGA.

SQL> select sum (bytes)/1024/1024 from v$sgastat where pool=’shared pool’ and name not in (’free memory’);

The total allocated memory for shared_pool in the init.ora or spfile can be detemined by

SQL> select value from v$parameter where name=’shared_pool_size’

I found a customer package consuming 400 megs of shared pool, i stopped the execution by killing the session and the problem was gone.

Tuesday, December 2, 2008

VxVM drop plex/mirror from volume and rename plex

Today i had to do some work on a storage system where new storages where installed and the old one should be unconfigured from the system.

By using

sh#> vxprint -g $DISKGROUP -rtLv $VOLUMENAME

i checked what mirrors (plexes) are available for the volume.

I selected the mirrors located on the old storage an dropped them from the volume with

sh#> vxplex -o rm dis $PLEXNAME

I noticed that the naming convention, after deleting the older plexes, does not look really pretty, because when the plex was created VxVM added a sequentiell number add the end of the plexname, so i decided to rename the plexes.

This was done with:

sh#> vxedit -g $DISKGROUP -p rename $OLD_PLEX_NAME $NEW_PLEX_NAME

After that all looks pretty well.