Re: Some very basic questions

[Christoph Hellwig <hch@infradead.org>]

On Tue, Oct 21, 2008 at 07:01:36PM +0200, Stephan von Krawczynski wrote:
> Sure, but what you say only reflects the ideal world. On a file service, you
> never have that. In fact you do not even have good control about what is going
> on. Lets say you have a setup that creates, reads and deletes files 24h a day
> from numerous clients. At two o'clock in the morning some hd decides to
> partially die. Files get created on it, fill data up to errors, get
> deleted and another bunch of data arrives and yet again fs tries to allocate
> the same dead areas. You loose a lot more data only because the fs did not map
> out the already known dead blocks. Of course you would replace the dead drive
> later on, but in the meantime you have a lot of fun.
> In other words: give me a tool to freeze the world right at the time the
> errors show up, or map out dead blocks (only because it is a lot easier).

When modern disks can't solve the problems with their internal driver
remapping anymore you better replace it ASAP as it is a very strong
disk failure indication.  Last years FAST has some very interesting
statitics showing this in the field.