Re: tapefs

Michael Wilhelm (michael@mydot.com)
Tue, 15 Sep 1998 18:54:38 -0500


> Michael Wilhelm writes:
> > I am looking for a tapefs or some type of program that may make a
> > nfs server using the tapedrive as a disk drive or a ftp server that
> > uses the tape drive as a disk drive... I have seen
> > unitree(www.unitree.com) but its not for linux.. any suggestions?
>
> I'm not entirely sure what you mean by "tapefs". I looked at the
> Unitree WWW pages and it appears the only product they offer is a
> heirarchical file storage system. This is a system which will backup
> unused files to long-term storage media (i.e. tapes). The file entry
> still appears in the filesystem (as would the inode permissions and
> such), it's just that the data blocks are marked as not available.
> When a process tries to access the data blocks in such a file, the
> data is migrated back to disc (obviously this can be a slow
> operation:-). These systems have a robot tape-loading machine
> associated with them and a roomful of tapes.
> However, this is not what I'd call a tapefs. I'd call it
> a heirfs or something.
>

> To me, a tapefs is a FS that allows me to mount a tape and gives the
> appearance of a (cough) slow filesystem. This is something I've had
> users (colleagues with large scientific datasets) ask me about, and is
> something that would be quite handy.
>
> So, implementing a real FS module for each of these systems would
> probably be the right way to go. What we need is someone with the time
> and energy to go forth and write code. Any takers?
>
I have an Idea on how to write a sudo tapefs or tapeftp worm, I just
don't know enough about c to go this low level.. but here is my
Idea.. Place all the directory structures on the Hard drive place all
files on the tape. so if your browsing the drive it looks at the
directory structures database (i.e. and ls or cd) but if you need a
file then it goes to the file and retrieves it and places it on the hd
until the file is closed then it is deleted.. here is how the directory
structures works and I am sure that this could be optimized: for
every directory there is a file there is a masterfile (like the
superblock) too. each file would look sorta like the ls -l like this:

permissions filelocation filename
drwxr-xr-x root root 0 directoryfilename2
-rwxr-xr-x root root 53224 filename

------------
Michael W.
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