Sparse Files

OK, I heard the term before but never had to really delve into them. That's an interesting concept, though. First delved into it needing a large (multi-terrabyte) file to house a file system. See here.

Then came across this article:

Sparse files – what, why, and how

I like the concept - though it does come with a few pitfalls, it seems. More on that later.

SSHFS and AutoFS

Mounting an SSH-accessible remote directory automatically is a nifty capability. Here's a nice description of how one can do that - specifically under Ubuntu but it will work the same just fine under most other Linux distributions:

Automatically mounting a remote directory in Ubuntu using autofs + sshfs

One thing not mentioned there - and something I keep forgetting about between the instances I need to recall it - is that the passwordless SSH login will fail unless the user directory on the SSH server is writable by the owner only! So, using the same terms as in the example above one should do the following:

1) Log into example.com as remoteusername

2) Execute the following command:
chmod g-w,o-w ~

A forgetful filesystem

We have this laptop running Open SuSE 10.1 installed on a ReiserFS. Recently all of a sudden a file - and a hidden file nonetheless - reverted to the contents it used to have at least several months prior. It being a hidden "dot" file makes it highly doubtful the owner modified it by mistake.

I am, quite obviously, a bit surprised here... The only explaination that comes to mind is that ReiserFS being a journaled filesystem, it for some reason rewound the journal. Now why it would do it - I have no clue. If you know the secret feel free to use the comments to enlighten yours truly and the others in the dark.