Find architechture of installed RPM package

When trying to find a rpm package on a 64 bit installation of Red Hat, you will sometime encounter two packages with the same name:

# rpm -qa zlib

This happens when a 32 as well as a 64 bit package exists on the server. If you want to find out which is which, you will have to use a somewhat trickier rpm command:

rpm -qa --qf "%{n}-%{v}-%{r}.%{arch}\n" zlib


Howto extend a ext3 filesystem in RHEL5

In RHEL5 ext2online is no longer available. However, do not despair – you can still grow your ext3 filesystems while online: The functionality has been included in resize2fs so to resize a logical volume, start by extending the volume:

# lvextend -L +2G /dev/systemvg/homelv

And the resize the filesystem:

# resize2fs /dev/systemvg/homelv (by omitting the size argument resize2fs defaults to using the available space in the partition/lv)

Expire password in Linux

If you need to force a user to change password at next login, simply use:

# chage -d 0 <userid>

Keep track of failed login attempts

To enable faillog to actually start logging failed login attempts you need to set up PAM to use the module “”. To configure PAM open the file /etc/pam.d/system-auth in your favourite editor and add the following lines to the file:

auth required onerr=fail deny=5
account required

This should make sure that accounts are locked if the number of failed attempts exceeds 5. The counter is reset on successful login.

The behaviour of pam_tally has changed over time – this approach should work on at least Fedora Core 6+, RHEL 5, SLES10 and later.

In SLES 10 the PAM config-file is /etc/pam.d/login

Finding Disk ID on a Raw Device Mapping in ESX

vmkfstools is your friend. In ESX 2.5.x you can use the switch “-P” on the “mapping”-file to show you details of the RDM.

# vmkfstools -P /vmfs/FileSystem1/somemachinesdiskfile-META.vmdk

in VI3 the switch has changed to “–queryrdm” or just “-q” for short.

# vmkfstools -q /vmfs/FileSystem1/somemachinesdiskfile.vmdk

Howto change MTU in Red Hat Linux

In Red Hat Enterprise Linux you can change the MTU (Maximum Transmission Unit) dynamically

# ip link set mtu eth0 512

or using ifconfg

# ifconfig eth0 mtu 512

but to make it permanent even after a reboot you need to add the MTU setting to the correct interface configuration file.

continuing the above examples, that would be:





Qlogic HBA WWN’s in SLES 9/10

If using Qlogic HBAs in SLES 9, the recommended driver is the vendors own driver. In this case wwn's as well as wwpn's could be found by looking in /proc/scsi/qla2xxx
# cat /proc/scsi/qla2xxx/* | grep node


# cat /proc/scsi/qla2xxx/* | grep adapter-port

In SLES 10 the native HBA driver is the recommended. You can find WWNs and WWPNs by looking in /sys/class/fc_host or using the systool

# cat /sys/class/fc_host/host?/node_name


# systool -c fc_host -A "node_name"


This Blog is not really a blog. It is meant as place to write tech stuff that I would otherwise forget. So it’s pretty much a private bulletin board.

On the other hand; If this collection – by any chance – can help somebody “out there”, it would be downright stupid not making it public. With the added bonus that I can access my “memory” from anywhere as long as I’m online (which is pretty much allways).

There’s not much (read: nothing) in this collection yet, but there will be shortly, and it will be a work in constant progress.