Re: raw backing store

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 28 Jun 1999 11:53:45 +0100 (BST)


> I'm wondering what you do if you have 170gb of cheap, 20ns sram-workalike
> on a chip instead of instead of disks. How do we leverage the efficiency

You run off and sell it to the NSA. Actually with that spec of toy I'd
expect the department of interesting toys would buy you out and sit on it

> of that in the kernel? Do we still need a filesystem, ie some number of
> huge ramdisks that are persistent? Or do we just have a database of
> persistent objects, where a filesystem is just a particular view of it
> (for the use of legacy software)?

You need a file system to put files on any media.

> store are the same physical bytes. Your disk and ram are indexed by the
> same vm system. As soon as your code creates a data structure in memory,
> it's already "saved". A "file" is just a range of bytes in ram, and a

And your memory leaks are saved, your saved structure isnt platform portable.
The pointers in it go bad if they point to transient objects someone else
has.

> little. The filesystem isn't going to need to be able to optimize for seek
> time on rotating/tape-streamed storage, so forward-looking index designs

Thats fine. You still need journalling , you still need recovery from
corruption. 20Gig is a lot of cosmic rays etc 8)

All that changes is the disk layout becomes a little less important.

Alan

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