Re: The store interface

Duane Wessels wrote:

> The swap file number is unrelated to the filesystem layout. There
> is a one-to-one relationship between a StoreEntry and a swap file
> number. Thus, a single object may not occupy multiple sfileno
> locations.
>
> The swap file number is an index to the filesystem "directory." That
> directory can specify which "block numbers" or filesystem units are
> occupied by that file number.

I know that. But in my opinion it should be up to the filesystem to
determine the value of this index, or else some layouts will require an
additional level of indirection.

Today we have with UFS

URL (map) Store Key -> swapfileno (map) cache_dir,filename -> inode
(object) -> disk blocks

The point I was trying to make was that it should be up to the
filesystem to allocate the part of swapfileno which UFS uses to map to
filename. That way a disk block based cache filesystem where the get the
path down to

URL (map) Store Key -> swapfileno (map) cache_dir,object

Instead of

URL (map) Store Key -> swapfileno (map) cache_dir,swapfileno -> object

For UFS the change will allow UFS to select where in the UFS mainained
cache_dir the file should be located.

/Henrik
Received on Tue Jul 29 2003 - 13:15:59 MDT