[geeks] Gold archival CDs?

[Charles Shannon Hendrix]

Mon, 22 May 2006 @ 14:41 -0400, Patrick Giagnocavo said:

> On Mon, 2006-05-22 at 12:36, Lionel Peterson wrote:
> 
> > The key points in this (for me) was the lack of manual intervention to
> backup files,and the "always available" nature of files. Also, IIRC the Plan 9
> clients were "typically" thin clients with minimal/no local HDs.
> 
> Actually they put everything on WORM drives each night.  There was not a
> hierarchical storage setup, just everything getting burned to WORM each
> night under a date-stamped toplevel directory.

Not quite.

You don't "burn" data to WORM drives. The way they work is you never re-use a
given sector twice. It requires filesystem code that can handle this.

The WORM drives in Plan 9 were used "live", with hard drives as a cache
for them. It was an automatic process. 

The hard drives acted as a cache so that several file operations could be done
without having to write to WORM, and they could checkpoint at any time without
affecting user access to files. Users accessed snapshots using a secondary
read-only mount of the filesystem.

They could recreate the entire filesystem any time by rebuilding the cache
data if the system came down hard and lost its data.

You can download the original paper here:

http://citeseer.ist.psu.edu/16216.html



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shannon "AT" widomaker.com -- ["Trouble rather the tiger in his lair than
the sage amongst his books For to you kingdoms and their armies are mighty
and enduring,  but to him they are but toys of the moment to be overturned
by the flicking of a finger." - anonymous     ]