DreamBox DM600PVR

So after years of ignoring the compact pc I purchased to install MythTV on to use as a personal video recorded with added bonuses like network connectivity and ability to add modules to increase functionality I decided to leave it tasked as a email/web server and invest in a shiny new DreamBox. I have only seen dreamboxes in Egypt and most of those quite old models so I had a look to see what was on offer and found a number of interesting units. The daddy of them all the dm8000 has dual tuner internal hdd support and hd support but wasn't out yet so I turned my eyes to the dm800 its smaller brother who has the same features but with one tuner but sadly still a big price tag for someone like me who doesnt have a HD tv and isn't that interested in owning one in the near future. The next in the lineup to me seemed to be the new dm600pvr although often ignored due to lack of dual tuner like the 702x range it's small size and reasonable price made it very attractive to me.

The dreambox was simple to setup out of the box and occupied the same space under my tv that my sky digibox had done plus an extra cable to give an internet connection via my sky netgear router. Upon scanning for channels I realised I had an issue as by default it doesn't have any softcams which emulate provider encryption services so you can't use your sky card or someone else sky card id(not currently possible for NDS the system sky uses but possible for other providers) or share their sky card over the internet for example to decrypt the channels you usually get and some you don't usually get. I chose to go with the softcam CCcam but the Enigma image that comes on the dm600pvr is a little fiddly to add software and manage softcams with and turns it more into linux sysadmin work so to allow everyone in the house to have a play I replace it with the latest Gemini image which was 4.40.

Upgrading the image wasn't the simplest of process not having windows to hand or a working serial port and hearing tales of woe from people trying to use usb->serial cables I googled and found that if you fix your dreambox IP address on your DHCP server so it's now static then telnet to it and type the following:

mount /boot -o remount,rw
rm /boot/*
reboot

Once rebooted if you hit the web interface it gives you an option to re flash the unit with the image of your choice!

Now Its just a matter of using the blue menu / addons and download CCcam and a config file for it then select CCcam in the blue menu. Sky cards now work in the front slow and you have the ability to download the latest keys from satanddream ready for manual install in Gemini which is a user contributed source of keys for opening up more channels. There is much more you can install or addon but I recommend MultiView or MV for EPG which you can feed using xmltv project and their radio times script.

Man Page Bugs

Just noticed CentOS5 has a man page bug and may not be the only disto to have it as when I google for the same man page I get similar results.

Compare man mkfs.ext3 to http://man-wiki.net/index.php/8:mkfs.ext3

You will notice the following is missing:

-I inode-size

Specify the inode size. The default inode-size used by mke2fs is 128. inode-size can be 128, 256, 512 or

1024. This value generally shouldn't be changed!

It almost led me to recreate a filesystem with the wrong option as I did not believe GlusterFS docs would be more complete than my current distros.

RedHat Installer aka Anaconda

What an annoying inflexible tool! It reminds me of Windows in it's methodology e.g. abstract everything from the user so that he doesn't have to know anything, hide real problems from the user so he doesn't know whats broken and then won't worry, stop the user from being able to manually setup anything so he can never fix any problems that occur from the automated fashion the installer uses. What happened to the rescue shell that used to start back in the day giving you some flexibility? What happened to the option of loading another driver at install time from supplemental CD/DVD or the Internet? What happened to the ability to partition using fdisk or something seperate from the anaconda script?

IMHO all this type of thing breeds is a new type of Linux admin very similar to a Windows admin of late who can only follow others step by step work and heavily reliant on Wizards and management GUIs while pissing off the experience Open Source community members who are forced to use distributions like these because of their support structure and market share.

Dell Hell

Had to contact Dell today for some assitance with their new PowerEdge 2950 servers we have just bought. We planned to run raid6 on all 6 drives and use that both for the OS and storage.

Seemed like a good plan till I realised partitions => 2GB are not supported without efi support but more importantly grub and lilo can't boot EFI/GPT configured drives.

There however is a workaround for this in the form of a linux kernel driver for EPI support to access those big partitions called efivars and a boot manager called efibootmgr which seems like a modified version of lilo.

The kernel module required seems to be included with the currently linux kernel in RH/Centos 5.1 but the efibootmgr http://linux.dell.com/efibootmgr/ needs to be installed and the disk partioned with an EFI partition for boot at the start of the disk as outlined in http://www.centos.org/docs/5/html/Installation_Guide-en-US/s1-diskpartitioning-x86.html.

Seems simple enough but as an admin used to fdisk I could not achieve this in DiskDruid without some further instruction.

On calling Dell support I was told that support can not be given as I'm not using thier OEM RH 5.1 CD and rather a downloaded version without their branding which would have no effect on issues I could face yet they still leave me unsupported!! After explaining for 10 minutes the situation did not change, and asking to speak to a supervisor resulted in the original operator rejoining the conversation to re iterate how Dell support will not help to resolve this issue and ending the conversation in a manner that led me to believe that was the last I'd hear from Dell.

However, today just as I had finished cussing Dell support I had a phonecall from a knowledgable chap with an Irish accent who talked me through possible options and one I was not aware of before. Raid on the raid controller supplied with the PE 2950 can be configured to create virtual disks on the raid arrays and unlike I had guessed you can have more than one of these per raid array so it's possible to create a small virtual disk that grub/lilo can boot and still use one raid6 array so no space is wasted :)

Just wanted to add the first support op who I spoke to called me back yesterday to confirm my resolution was successful. I'm still not clear if I miss understood the original operator and I was to be helped he just wasn't positive I'd get the support I needed as other customers haven't had success or if my call was listened to and a different action to the usual decided on since I presented myself as a very influential client.

GFS - Global File System

Thought I'd add my thoughts on GFS since the documentation on the net currently seems very fragmented and incomplete:

Large files can cause slowdown issues.

Machines really need 2 nics one for client access and one for access to the SAN, cluster communications and communication with the fence device.

The fence device is in most cases a APC power strip so when a node fails the other nodes can reboot that machine as part of the failover process, the other option is to close the switch port of that machine so it cant access the SAN data which IMO is worse than a reboot since recovery needs manual intervention.

When creating the GFS you need to have an idea how many nodes you are going to need as you cannot add more. I have read places that there are limits on the amount of nodes, it used to be very small(16) but now its over 100 for sure might even be 300 odd but each place I look I get a different value. We need to decide on how many we may eventually have I'm thinking just set it to 125 as I doubt we would ever have 125 web servers but then if things go well this statement could come back to haunt me in my sleep ;)

If we need to give access to the data to machines not in the cluster perhaps ones that don't use the data much we can use GNDB on each of the servers in the GFS cluster so they can be connected to as a network block device and data read and written to(albeit in a slower manner than if just gfs was used and creating more traffic on the client side of the network)

I can see no other real alternatives to GFS other than Veritas' expensive offering.

I can see now though after some heavy googling it should be possible to install gfs+clvm on both NAS servers to share the space they have in them and then anything linux can use gfs to talk to these but windows clients would be forced to use samba running on the NAS servers.

Handy shell commands

Dealing with broken things always tends to further my knowledge. Recently I discovered the following tips and tricks:

ls -d */ = Lists directories in the current directory.
disown = Disconnects a process fomr the bash session ready for logout if you have not already redirected the output.
nohup = Starts a process backgrounded and writing to nohup.out.
mkdir -p = Makes a directory and makes the parent directories if missing.

Rsync documentation bug

It seems developers still haven't got the hang of documentation ;)

Rsync is supposed to support the --password-file option and and env variable and for about a day I just assumed it was broken. It is not is seems the above options are only for use with rsyncd and not sshd forcing the user to use keys if they need to script rsync connections via ssh.