Louwrentius

My router decided to change the device name for some USB storage devices. So /dev/sdc was swapped for /dev/sdd and vice versa. The result was some file system corruption on /dev/sdc, because it was used on a remote system through iSCSI, using a different file system from /dev/sdd.

With regular internal disks, attached with PATA, SATA or SAS, the chances are very small that such an event will occur, but it is possible, especially if you start adding/subtracting disks. With USB devices the risk is substantially bigger.

To prevent your system from mixing up drives because there device names change, use file system labels. All information that follows have been stolen from this location. Since this blog is also my personal notepad, the relevant bits are reproduced here.

There are three steps involved, the third being optional:

1. add a label to the file system
2. add the label to /etc/fstab
3. update grub boot manager (optional)

Add a label to the file system

Setting a label when the file system is created:

mkfs.ext3 -L ROOT /dev/sda1
mkfs.xfs -L BIGRAID /dev/sde

Set label for existing file system

EXT3:

e2label /dev/sda1 PRIMARY_ROOT
e2label /dev/sda1

XFS:

xfs_admin -L DATA1 /dev/sdf
xfs_admin /dev/sdf

Set label for swap partition

mkswap -L SWAP0 /dev/sdb5

add the label to fstab

Example of contents of fstab:

LABEL=ROOT          /         ext3    defaults        1 1
LABEL=BOOT          /boot     ext3    defaults        1 2
LABEL=SWAP          swap      swap    defaults        0 0
LABEL=HOME          /home     ext3    nosuid,auto     1 2

Update the grub boot manager

title server
root (hd0,0)
  kernel (hd0,0)/vmlinuz ro root=LABEL=SERVER_ROOT0 rhgb quiet
  initrd (hd0,0)/initrd.img

Most web applications work like this:

The application uses a single database account to perform all actions. Users are just some records in a table. Account privileges and roles are part of this table, or separate tables.

This implies that all security must be designed and build by the application developer. I think this is entirely wrong. There is a big risk:

In such applications, SQL-injection will allow full control of the entire database.

This is something that is often overlooked. And the solution is simple. The application should not use a general account with full privileges. The application should use the database account of the user accessing the application. All actions performed by this user are thus limited by the privileges of this database account. The impact of SQL-injection would be significantly reduced.

The public part of a website is still using an application account, but the privileges of this account can be significantly reduced. To obtain elevated privileges, a user must first authenticate against the application and thus the database.

Please understand another benefit: it is not required to store username/password combinations of privileged accounts on the application server. The configuration file will only contain the credentials of the unprivileged account. An attacker compromising the application server with limited privileges, won't have access to the database with elevated privileges.

I understand that this solution requires a bit more work to setup at the start, but once implemented, it reduces complexity and improves security so much.

Of course, the security of your data is as good as the hardening of your database server. But that's another story.

Most people just don't understand computers. Are these people dumb? Some may be dumb, but the people who make them are maybe even dumber. Because they can't seem to figure out how to create a computer that the majority of people understand.

When the original macintosh arrived at the stage back in the eighties, computers became a bit more human-friendly, but it was limited to the constraints of the then available hardware. It put away the text-based interface and introduced the graphic interface. It used the desktop metaphor to create this graphic environment. But this metaphor has had its day.

Many people don't understand the desktop metaphor since they don't have a desktop and have never used one. Also, it is a metaphor, it's to translate the computer environment to something humans understand. But what if they don't understand the metaphor? For example, many people just don't 'get' the Windows Explorer or the Mac OS X finder. The desktop metaphor does not seem to fit in how people think.

Every time you see a person enter a URL like www.youtube.com in the google search field, you will realize that we still have a long way to go.

Most people did not seem to realize back then that the release of the iPhone wasn't that important, but the release of iOS. The iPhone was the first smartphone (a word most people are not familiar with) that did away with a stylus or hardware keyboard. It uses what is closest to us: our fingers. A totally new user interface, one that is very natural and close to us, is now available.

Using touch as input required a total redesign of the entire user interface. All other interfaces were designed around hardware keyboard and mouse devices. Fingers are big, and are obstructing the view. But it allows for a more direct interaction with a device. And now all new smart phones sport a touch interface.

Rumors of an Apple tabled existed for long, but it was very clear when the iPhone was released that if Apple would release a tablet, it would run this new iOS operating system.

When the iPad was released, it became an instant hit. As of today, there is no device on the market that can be truly called a competitor. But why is this so? The ground work has been done by the iPhone. Most people with an iPhone will notice that aside from some performance issues in the past, the device just always worked. It was instantly available to sent an email, look something up on wikipedia or find the nearest Starbucks. An iPhone just always works. No boot. Very reliable. And an interface that makes you happy.

Why does iOS make people happy? Because it provides a user interface that is human. People understand it instinctively. Any person of any age or background will be able to use an iOS device within minutes. The interface doesn't make you look like you are dumb because you just don't understand how it works. It not only works, it is easy to use and you are not afraid to break anything.

The iPhone and the iPad are learning a lot of people not to fear computers.

The iOS does away with the old desktop metaphor, but so does Symbian or similar interfaces. It is the combination with touch and the well thought out interface that sets it apart from other mobile operating systems. Even when the iOS platform did not have native applications, people still bought it and not only because Apple released a new shiny toy.

However, the app store on iOS has created a very special and important environment. People can finally install and remove applications in an extremely simple way. They don't need to be scared that some program will crash your computer either while installing it, using it, or removing it. The whole iOS ecosystem creates an environment wherein people don't need any help any longer from other people. They are finally in control. They don't need to be afraid of their computer.

This trend will affect the old-school user interfaces such as Mac OS X. How it will turn out is anybodies guess. But there is at least a small trend to 'eradicate' the finder as much as possible. iPhoto stores your photos. iTunes stores your music. If you want to include a photo or song within an application, you pick the photo or song in question from a miniature iPhoto or iTunes interface. There is no finder anymore. The finder is disappearing from the workflow. And why not? If programs are written well, why bother with it? The finder should be abstracted away, as is the case on iOS, where you don't have a finder.

Another thing is multitasking, you know, that stuf we like to do, but cant. We can only do one thing at a time. What we do want is fast task switching, not multitasking. Sure, some programs must be running in de background, to continue to operate, such as a chat program, but that is not the point. Most people are just going crazy if you show how multitasking works, with different windows. Again, iOS shows how 'multitasking' should be implemented. It is implemented as fast application switching, allowing these applications to register services that must continue to run, while the application itself freezes when the user switches to another application. People tend to use one application at a time and especially on mobile devices, every single bit of screen real estate counts, so they are always running full screen. This full screen notion will also be incorporated in the next Mac OS X release, Lion. People switch, but do one thing at a time.

Computer nerds tend to feel superior to people who don't have much skill using a computer. This feeling of superiority is totally misplaced. They should be really humble. because up until the advent of iOS, nobody was able to create a human friendly computer interface. It is not the lack of understanding on the side of computer users, it is the lack of understanding on the part of the computer nerds on how normal humans think and act.

Simple, human friendly computer interfaces will liberate humanity from those pesky computer nerds. And that will cause a bit less suffering in the world I hope.