Recovering files after a crash

[Sebastian Seidl]

Erik Norgaard wrote:
> Roland Smith wrote:
>> On Wed, Aug 19, 2009 at 09:59:32AM +0200, Erik Norgaard wrote:
>>> Thanks, I couldn't decipher these GEOM_LABEL messages, nice to know 
>>> that I can stop worrying. But for future incidents, the second 
>>> question remains:
>>>
>>> 1. How do I best protect my system from disk errors in case of a crash?
>>
>> One word: _backups_!
>>
>>> I have a headless system with no spare head to attach and doing 
>>> single-user blind-folded is further complicated by the fact that I'm 
>>> not native to the US keyboard layout, so my top priority is that it 
>>> boots.
>>
>> If you can connect it to another system (that has a monitor) via a 
>> serial
>> null-modem cable and you enable the serial console (see the 
>> Handbook), you can
>> watch the boot process from the other system.
>>
>> If you don't have anothe machine closeby, you should get a 
>> network-accessible
>> KVM switch with serial connectors. [maybe something like this:
>> http://www.knuerr.com/web/en/products/kvm/kvm-switch-dominion-ksx.html] 
>> With such a switch and the serial console you should be able to watch 
>> the boot
>> of the machine remotely.
>
> Ok, maybe I didn't make myself clear: I wish to protect my filesystem 
> against corruption in case of a crash such that it will boot.
>
> - How can I configure my system to reduce the probability that a crash 
> will cause file system inconsistencies that require single user mode 
> intervention?
>
> backups does not answer that question, they are great for recovering 
> lost data but don't prevent the crash.
>
> KVM and serial console don't answer the question either. Certainly, it 
> makes it easier to work headless. But neither prevent disk corruption.
>
> UPS reduces the likelyhood of a crash in case of a power failure, but 
> that doesn't answer the question either.
>
> Asume that a crash will happen, how do I prevent or reduce the risk of 
> a crash causing disk corruption such that the system will boot up 
> nicely again?
>
> BR, Erik
If u want to reduce the posibility of data corruption I sugest using a 
smart UPS with management software installed and configured so that 
before battery power goes out it will do a clean shutdown and also 
restart the system when AC power is restored (see apcupsd).
That is what I'm using.

Regards,
Sebastian Seidl