Bad blocks in journal area of ext3 fs due to bad strategy.

[deva]

Hi

I have a media center box running gentoo that is often turned off by just pulling the power rather than doing a nice 'init 0'.
Since audio/video recordings are often made on the box I have added data=journal,commit=1 to the mount options on the partition storing the recordings.
The full fstab entry is:

[Hu]

Although you may be able to mitigate the damage done by a hard power loss, you should try to avoid this as best you can. Only cut power if the machine is hung. Otherwise, turn it off properly. You can turn off journaling entirely if you want to write changes through without the journal, but this is bad for performance.

[deva]

Thank you for your reply.

[The Doctor]

What is wrong with using ssh? You could make an alias on your normal computer, say haltserver or something, which would would log in and send the power off signal with a single command.

EDIT: Even if you can get it down to a 1/1000 chance of damaging your system by pulling the plug (and I don't think you can get odds that good) you will have a 30% chance of damage within a year and 70% with 2. That seems like an awfully big risk.
_________________
First things first, but not necessarily in that order.

Apologies if I take a while to respond. I'm currently working on the dematerialization circuit for my blue box.

[Goverp]

[Hu]

Does the media PC not have a power button that you can press? The standard way to turn off such machines is to bind an ACPI event to the power button, and let that event trigger a software-initiated halt when the user taps the power button.

You may be able to disable the journal with tune2fs. I doubt you can do it with mount options for ext3.

I believe The Doctor was working from basic probability. If we assume a .001 chance of damaging the system through an unclean shutdown, then you have a .999 chance of not damaging the system with the shutdown once. You then have a .999^2=~.998 chance of damaging the system with two shutdowns. Extend this out to a year of halting the machine every day and you get .999^365=~.694 chance of not damaging it after 365 shutdowns and a .999^(365*2)=~.481 chance of not damaging it after 365*2 shutdowns.

[Goverp]

[Hu]

I disagree, for two reasons. First, clean shutdown is exercised by far more people than unclean startup. Second, the clean shutdown case proceeds in an orderly fashion and by definition is never interrupted in the middle. If it were interrupted in the middle, it would be an unclean shutdown, whether that interruption is because the user removed power or because the kernel crashed. In the unclean startup case, the damage is presumed to occur not because of an unclean startup, but because of the unclean shutdown which preceded it. By definition, the unclean shutdown is halted at some point that has not properly synchronized its state. There exist a huge number of such points in the normal operation of a system, many of which are probably hit rarely if ever by users. Though I hope no one sells consumer hardware like this, there is a chance that the machine has components which can be damaged merely by the electrical aspects of an unexpected power loss, but which would be fine if properly halted before electricity was cut.

[wjb]

A variation on The Doctor's suggestion - a tiny custom weberver running on the mediacentre to do a shutdown when a given page is requested, and a bookmark to that page on your phone.

[Ant P.]