FC write policy?

[Bjameson]

I think I have a pretty good idea how FC caches its write data. But just to make sure, could you please answer this:

Suppose I have 256MB of L1 and 3GB of L2 to hidden memory. Write delay is set to 300 secs.

I create a 1GB file and immediately delete it again. How will FC handle this?

- FC eventually writes the entire 1GB to disk, followed by the delete.
- FC is smart enough to delete the file from the cache, thus preventing writes to disk altogether.

I'd be very interested to know for sure.
Thanks.

[Support]

Hi Bjameson,

Currently FC is not smart enough.
So the answer is this one,

FC eventually writes the entire 1GB to disk, followed by the delete.

[Christodoulosk]

What happens when a file is on the cache and before it is writen in the disk the file changed?
Is the writen file on the disk the changed one?


Sorry for my English

[Support]

What happens when a file is on the cache and before it is writen in the disk the file changed?
Is the writen file on the disk the changed one?

Yes, the data written to the disk is always the latest in the cahce.

[Christodoulosk]

So it is correct to asume that the total writen data on the real disk is fewer when the FancyCache is on. ?

[Support]

theoretically it is. But because of the program implementation limit, sometimes it isn't.

[Support]

Now the write amplification bug has been fixed in version 0.4.1. So the total written data to the real disk is fewer if defer write is on.

So it is correct to asume that the total writen data on the real disk is fewer when the FancyCache is on. ?