Marek Mahut

Recently I bought an external USB Disk Seagate FreeAgent XTreme, but after some idle time, it spanned down. Take me a while to find out how to disable this standby mode. First install sdparm.
If you want to start the drive in standby:
sdparm –command=start /dev/sdb
To clean standby mode flag:
sdparm –clear STANDBY -6 /dev/sdb && sdparm -a [...]

Did it ever happen to you by mistake to add one additional digit into dns serial number? Ooops! Now, how to fix it?

Increase the serial number to (2^31) – (correct serial number) and reload named. For example 2^31-2009010602 = 138473046. As DNS serial numbers are signed integers, this make server thinks that it’s a negative [...]

If you are using clustered service with kerberos, you may want to merge hostnames keytab files to one for simple distribution.

Create host and service principals.

kadmin: addprinc -randkey host/node1.corp.intranet.lan
kadmin: addprinc -randkey host/node2.corp.intranet.lan
kadmin: addprinc -randkey host/node3.corp.intranet.lan
kadmin: addprinc -randkey host/node4.corp.intranet.lan
kadmin: addprinc -randkey host/node5.corp.intranet.lan
kadmin: addprinc -randkey host/node6.corp.intranet.lan
kadmin: addprinc -randkey host/node7.corp.intranet.lan
kadmin: addprinc [...]

Mike McGrath, the Fedora infrastructure lead, made an awesome presentation on puppet and how to use it. Slides and audio record are posted at http://mmcgrath.fedorapeople.org/puppet/.

From time to time, I need to clean my disk from useless stuff I’ve installed over time. It’s just amazing how much of packages I can install during debugging and configuring every day. If I’m short of disk space, I start first by reviewing biggest packages on my system:
[mmahut@mmahut repo]$ rpm -qa –queryformat ‘%10{size} %{name}-%{version}\n’ [...]

I’ve found a very nice link explaining how to hold a binocular for sky observation. My preferable is number 3, but I’ve never tried fourth variant. You can also learn something about binocular mounts on that page.

There are tons of articles like this one on the internets, thus I’m just writing this down as my personal note. First let’s check for the package.
[root@mmahut ~]# rpm -qa cryptsetup-luks
cryptsetup-luks-1.0.5-7.fc8
[root@mmahut ~]#
After un-mounting /and backing up :)/ our home directory, we need to erase everything on it.
[root@mmahut ~]# shred -n 5 -v /dev/vg00/lvhome
shred: /dev/vg00/lvhome: [...]

I’ve found an interesting tool, it’s an interactive process viewer called htop. Try it out, it’s very nice.

Martin Ankerl compares on his blog the performance of several linux terminals.
I’m happy user of gnome-terminal :)

While looking for more information about ext4 filesystem, I found an interesting patch named ext3cow. It is a versioning file system based on ext3. And how it works?
[root@storm ~]# echo “Beee” > ~/kac
[root@storm ~]# snapshot
Snapshot on .: 1062987103
[root@storm ~]# echo “Meeeee” > ~/kac
[root@storm ~]# cat ~/kac@10629871034
Beee
[root@storm ~]# ~/kac
Meeeee
[root@storm ~]#
Unfortunately, due to performance and storage overhead, [...]