After setting up the alignment according to some tutorials I found online, I started the setup process. Shortly after starting the copy step of the installation, the whole process came to a grinding halt with filesystem errors. Looking into the kernel debug messages it seemed like SATA commands were causing errors. After checking hardware, cables and switching SATA ports, I began researching the issue and soon found that the issue might be fixed in the next firmware version of the drive. So I wanted to upgrade from 1.23 to 1.24, which could only be done in Windows…

After installing a trial of Windows 7, I finally wanted to upgrade the firmware, but the drive was not detected, but was accessible. The release notes indicated that I would need to switch to AHCI mode. After several attempts, includig a BIOS update, I realized that there was no way to do this with my old hardware, as my nForce 430 chipset simply doesn’t support it.

So my only remaining option was to simply try the kernel arguments I read to be the fix for 1.24 with the 1.23 hardware.

So, if you add the following kernel option during installation and afterwards for every boot, the disk seems to work quite well (source):

libata.force=norst

Actually, this forces the ATA driver in Linux to not issue any reset commands on the bus. I really don’t understand why this improves/fixes the problem, but it seems the device has issues when being reset on my chipset. I can also notice this that in 2 out of 3 attempts if I reboot the PC the disk is not recognized any more before I reboot again.

Despite these issues, the SSD now runs with astonishing performance with the suggested 32 head / 32 sector alignment, and a 512kB partition alignment scheme. After an initial TRIM with hdparm‘s wiper.sh I enabled -o discard for my ext4 partition and could also verify using hdparm that this results in the sectors being trimmed. Please note, that you need to manually compile and install the latest hdparm version on Ubuntu 10.10, as the included version fails with the very long free block list and doesn’t handle splitting the sectors in multiple requests. The latest version doesn’t have this issue any more.

If you tend to forget the number of times you already reset the counter, you can easily check for yourself: simply run

slmgr -dlv

to get detailed licensing information, including the number of remaining re-arms and remaining grace time.

If you want to know when exactly your grace period runs out, use

slmgr -xpr

Note: This simply gives you more time, it won’t prevent you from having to buy and/or activate Windows. Re-arming is not a bug, it works as intended and is an important tool for use in corporate environments.

The telephone number you have to set is *99#, which should be provider-independent.

The following settings are for yesss.at only:
Username: web
Passwort: web

Remember to set the APN as part of the driver’s connection string in Window’s “Device Manager” as described in the PDF.

Again, for yesss.at this is: AT+CGDCONT=1,"IP","web.yesss.at"

For this to work properly, the SIM must not have a PIN set, as otherwise the SIM will be locked and the dialer cannot dial out. For me this is ok, as it is a pre-paid card which can hardly be abused if it gets stolen, but your situation might be different, so please consider the security implications. (I suspect that it should be possible to unlock the SIM card somehow using the AT+CPIN=1234 command, but I did not research how to separate several initialization strings, as it did not work immediately.)

The solution works quite well for me, even under Windows 7. Disadvantage is that there is no way to tell the signal strength and exact mode of operation (despite the color-coded status led on the Merlin U740).

• Open the Control Panel
• Select “Programs”
• Select “Turn Windows features on or off”
• Scroll through the list, select “Telnet client”
• Press OK
• Wait (for surprisingly long)

That’s it, voila, the telnet client is now installed on your Windows Vista Non-Ultimate.

Sometimes udev renames your devices. This happened to me when upgrading a server, eth0 suddenly became eth1 and vice-versa. Of course, this broke nearly all firewall scripts on the server… There is a nice explanation how to get udev to name your devices the way you want.

Visual Studio 2005 Service Pack 1 on Microsoft Windows Server 2003

When installing Visual Studio Service Pack 1 under Windows Server 2003, it might fail because it cannot verify the signature. You should take time and visit the link provided in the error message, because it will take you to a hotfix that will correct the problem.

(via Mark Caroll’s Blog)

VMWare Server on Ubuntu 8.04

A nice tutorial for getting free VMWare Server 1.0.5 running on Ubuntu 8.04.

Trickle

Tricke allows you to limit bandwith for processes that do not support bandwith limitation out-of-the-box. It works by preloading and simulating the socket API. You use it as a wrapper when starting the process, like trickle -d 80 someapp.

You can use it to limit rsync speed for instance (thanks to http://www.yak.net/fqa/404.html): rsync -auvPe “trickle -d 80 ssh” user@host:/src/ /dst/

VMWare Tools and Kernel 2.6.24

VMWare Tools out of the box do not install on kernel 2.6.24 (as used in Ubuntu 8.04 for instance). A possible solution is described here. It is based on using the open-source version of the VMWare tools (open-vm-tools).

Primary tool in managing any network is using monitoring software which tells you if everything is alright or if you should worry. For various reasons I have become a huge fan of Nagios for monitoring networks I am responsible for, especially for the simple extensibility by writing your own check scripts (plugins).

While working through some issues in a network, I suddenly decided to try an approach I spontaneously called “test-driven network management”¹. The steps are easy (and are a one-to-one translation of agile software-development principles):

1. Write a Nagios test which checks for the requested/required feature.
2. This test will fail.
3. Implement a solution satisfying the test.

The same advantages of automated testing (better: unit testing) in software development also apply to the network management tasks:

• The test documents what you want to achieve in a quite formal way.
• You will (almost) immediately know when your solution breaks other requirements (if tests exist for them).
• As networks tend to be even more fragile then software, you have to monitor whatever you implemented anyways

Whenever possible, I try to add a test (or tweak an existing one) for any trouble-ticket / feature request I come around. In my experience, customer satisfaction tends to increase, because you start noticing problems before they do and you also implement measures to prevent the same problems to occur over and over again.

¹ I am quite sure there is another technical term for it, as I am quite sure I am not inventing anything new here… If you know how this is called by others, please tell me in the comments.

[tags]development, network, sysadmin, network management, test-driven development, nagios[/tags]

What I really like about the software and the company is that they don’t claim that their data will be safe forever at their location. They confess it is possible for a company to vanish. In order to prevent you from being locked out they have outsourced the storage to Amazon, which provides cheap storage on a “pay what you need” basis.

JungleDisk provides encryption of the documents using AES and only you can decrypt them. To be on the safe side you’ll always be able to retrieve your data, they have released parts of the code covering filename-mangling and encryption under GPL.

JungleDisk is available for Windows, Linux and Mac. As said, they provide a WebDAV frontend so any WebDAV client can interact with it. It also features a local cache to prevent needing to download a file on every access. There is also an automated backup routine.

Costs are reasonably. At the time of writing, JungleDisk costs 20 US-$ once, with promised life-long updates and patches. All you need to pay for is Amazon fees for your usage, which are at 0.15$/GB/month, 0.10$/GB inbound traffic, and 0.18$/GB outbound traffic. You see, you can store lots of data for around 10$ per month.

One big minus-side of this is that Amazon’s data-centers are very slow from Europe, I was able to achieve around 700-800kbit/s (90-100kB/s) from our office connection. On the pro-side, due to the caching and background transfer, you don’t notice that the transfers are so slow, unless you need to download something. As I am using it for automated backup, I hope to never have to download anything.

So if you are searching for an offsite backup solution, you should definitely consider JungleDisk.

Mozy comes in two flavors, a version for home-users which they call MozyHome (4.95$/month for unlimited storage) and a service for businesses, called MozyPro, which bills 3.95$ per computer, but also 0.50$/GB per month. I think the service would definitely be interesting but the storage costs seem to high for me. There is also “MozyHome Free” which provides you with free 2GB of backup storage. Maybe the recent purchase by EMC Corporation will change the pricing list (honestly, I don’t think so…)?

The idea of storing my confident data or even corporate data on remote servers not under my control is a little bit frightening, but in case you are able to believe they have not built a master-key in the software, it might be a nice option for offsite backups which definitely everybody should use. Maybe one should give the “MozyHome Free” a test-drive… Too bad there is no Linux version available.

If I can convince myself to try out the “MozyHome Free” I will write another report here.

First, I ran into troubles installing cygwin. I figured out, that it seems to work well if you run both the installer and bash in “Windows XP SP2 compatibility mode”. I needed to adjust the file system permissions of the cygwin folder to give me write permissions, though. (Note: you have to manually install the TK-libs if you want the GUI elements of git to work.)

But Git kept failing with “access denied” messages when trying to commit from command line. The failure message said it was denied access to git-update-index. I soon found out this is due to the “User Account Control” (UAC) default behavior of auto-detecting installers and prompting if you want to execute them with raised privileges. You can see if this is the case by running git-update-index manually from bash; if you get the UAC confirmation dialog you have this problem. It seems the substring “update” triggers this behavior. As the git-update-index is launched by git commit, it won’t display the confirmation dialog of Vista, so the execution will be denied.

There are two possible workarounds:

• Run bash with administrative privileges (not recommended!)
• Disable the auto-detection of installers by UAC.

I used the latter way. You can disable the auto-detection by following these instructions. Brief summary:

• Open the Local Security Policies
• Disable “User Account Control: Detect application installations and prompt for elevation”
• Reboot (the security policy will not be updated before!)

It should work now. You can confirm this by running git-update-index manually again. If you do not get the UAC confirmation dialog now, it worked. Try git commit now, and verify it is working. Of course, you will from now on have to right-click and “Run as Administrator” every installer you want to install, as most installers will require administrative privileges.

Update 2007-08-22: Reader EGarcia posted an interesting comment below: using the Microsoft Manifest Tool you can add an according manifest to the git-update-index.exe and git-update-ref.exe

Update 2009-02-12: Reader Kevin Broadey points out the best solution so far: create a seperate .manifest file for the affected files. He has provided an example for git-update.exe.manifest.