Obscure xinetd tip

If you have a "wait=yes" server bound to 127.0.0.1, you can get a syslog full of messages like this:

xinetd[25741]: warning: can't get client address: Transport endpoint is not connected

The trick is to add "flags=NOLIBWRAP".

THis bug report gives a clue as to the underlying cause: https://bugzilla.redhat.com/show_bug.cgi?id=108583

Migrating a guest VM with Xen 3.2

'xen migrate' didn't work - it hung, as others have reported.

It turned out to be as simple as:

1. Stop the original guest.
2. Copy the disk image and the config files ( in /etc/xen/vm) to the new host.
3. Execute 'xm create guest-name' on the new host.
4. Done!

Expanding a Xen image disk

I found various pages on this, but the instructions weren't quite accurate for openSUSE 11.0

1. Stop the guest.
2. Find the image file with 'losetup -a'
3. Make a backup copy.
4. Add (e.g. 4Gbyte) with:  dd if=/dev/zero bs=1024k count=4096 >> /xen/images/yourguest/disk0
5. Mount with: xm block-attach 0 'file:/xen/images/yourguest/disk0' /dev/xvda
6. Using fdisk, find the partition, and resize it.
7. Use resize2fs to increase the filesystem to fill the space, run fsck -f to verify.
8. Unmount with: xm block-detach 0 /dev/xvda
9: Restart the guest.

Recovering a Linux SW RAID1 volume

I had one disk of a RAID1 set, and wanted to recover the data from some LVMs on it.

Turned out to be quite straightforward:

1. Plugged the drive into another openSUSE 12.1 box with a USB-HDD adapter.

2. As root, did mdadm --assemble --scan

3. 'cat /proc/mdstat' showed me the md devices that were found:Personalities : [linear] [raid1]
md124 : active raid1 sdg1[0]
      506032 blocks super 1.0 [2/1] [U_]
      bitmap: 0/8 pages [0KB], 32KB chunk

md125 : active raid1 sdg2[0]
      155726004 blocks super 1.0 [2/1] [U_]
      bitmap: 19/149 pages [76KB], 512KB chunk

md126 : inactive sdf1[0](S)
      506032 blocks super 1.0
     
md127 : inactive sdf2[0](S)
      155734036 blocks super 1.0
     
unused devices: <none>

4. lvscan showed me the LVs on the volume.
  inactive          '/dev/system1/home' [70.00 GiB] inherit
  inactive          '/dev/system1/lclhome' [30.00 GiB] inherit
  inactive          '/dev/system1/root' [20.00 GiB] inherit
  inactive          '/dev/system1/swap' [4.00 GiB] inherit
  inactive          '/dev/system1/usr' [6.00 GiB] inherit
  ACTIVE            '/dev/system/home' [25.00 GiB] inherit
  ACTIVE            '/dev/system/root' [20.00 GiB] inherit
  ACTIVE            '/dev/system/swap' [2.00 GiB] inherit

5. Activated the LVs using 'vgchange -a y'

6. Ready to mount!

KDE4 and ssh-agent

Using KDE Wallet to store your SSH passphrase is now quite easy.

You need ksshaskpass installed.


Add a script to ~/.kde4/Autostart/ called (e.g.) ssh-add.sh, with execute permission, containing:

#!/bin/sh
export SSH_ASKPASS=/usr/lib64/ssh/ksshaskpass
/usr/bin/ssh-add

Next time you login, you'll be prompted for your KDE Wallet password, then your password.

Works well. Thanks to this helpful post for getting me started.