Messages in this thread | | | Date | Fri, 25 Jun 1999 01:48:46 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: File systems are semantically impoverished compared to database |
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Date: Thu, 24 Jun 1999 22:52:09 -0400 (EDT) From: "Albert D. Cahalan" <acahalan@cs.uml.edu>
No, not like that at all. Structured storage adds an extra allocation and namespace layer above the filesystem. This works in userspace, but the performance is poor.
I'm not convinced this has to be the case (that performance will be poor).
You can get the performance today by using directories, but that destroys usability. Documents need to appear as files to the user, so they must appear as files to traditional POSIX software. It isn't enough to patch a file manager. You'd have to bloat everything in the whole system, perhaps losing the performance!
That's why I suggested using a user-mode libc hack in cases where the document is opened as a flat file. The assumption here is that most of the time the (office suite) application will be accessing the albod in directory mode, where performance will be great. The only time there will be user-mode intervention is when a file manager has to treat the document as a flat file, at which point the approach I suggested should be just as performant as your NTFS "reparse point" approach --- with the added advantage that I don't have to implement "tar" in the kernel, which the "reparse point" approach requires. (OK, it's a loadable kernel module --- but it's still implementing "tar" in the kernel.)
- Ted
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