Re: RAMDISK filesystem idea/question

[David Jeske <jeske@igcom.net> writes:]

>is there any reason that a static RAMDISK filesystem could not be
>created by making a server which just allowed file-access to a pre-sized
>piece of RAM and then running a filesystem on top of that?

That would be easy enough to do already. Just:

mkfs_vfs -p /tmp/fs.img
/vsta/boot/vstafs /tmp/fs.img fs/tmpfs
(install contents)
umount /
mount fs/tmpfs /

>Is the compression algorithm used by GNU zip suitable for random access
>to the underlying data? I was under the impression that it was VERY
>stream oriented. (not that another compression could not be used in the
>middle, I was just wondering about GNU zip)

No, gzip is not compatible with random access. However, common block sizes
(4K and above) allow very good gzip performance when applied against these
little chunks. So it's quite possible to gzip each block, and then add
something so you can locate the beginning of each block (which, being
variably sized due to compression, can not be found at a fixed offset).

>I suppose one advantage of enhancing srv/tmpfs instead is that it would
>not have to be statically sized. However, this might be a disadvantage in
>the case of a boot-floppy.

Or, as in my example, you can static size a piece of tmpfs space and run
another filesystem.

                                                        Andy
Received on Sat Jul 1 05:23:00 1995