File system

[Nikos Vassiliadis]

Eitan Adler wrote:
> gjournal will replay all write attempts
>> (metadata and data) before the failure, so you should be relatively
>> sure that all writes are done correctly.
> 
> As I understand it journals work by writing to disk a log of all the
> changes that have to be made - waits for confirmation that it wrote
> the data - and then attempts to make those changes. If after the
> confirmation there is a crash the log file is replayed.
> Certain virtual machines will report to the OS that it wrote the data
> to disk before it actually does so. In that case journaling doesn't
> actually help as the log file is still not on some form of stable
> storage.


I am not an expert on the subject, I thought the journal will replay all 
logged write attempts and since the number of all write attempts logged 
in the journal will be much bigger than the number of requests a cache 
can hold you will be sure that all writes will be done on the 
filesystem. Again, I am not an expert on the subject...

Nikos