[Info-vax] New filesystem mentioned

[Bob Gezelter]

On Tuesday, May 14, 2019 at 12:32:35 PM UTC-4, Dave Froble wrote:
> On 5/14/2019 11:19 AM, Stephen Hoffman wrote:
> > On 2019-05-14 12:21:12 +0000, Simon Clubley said:
> >
...
> I really don't understand this concern.  If directory entries contain 
> some RMS metadata, and I think they do, that can just be ignored by 
> things that do not need the data.
> 
> >  Maybe BACKUP would then get fixed here too, assuming
> > BACKUP would not be replaced by an improved and faster design?  For
> > related details here, see the user- and API-visible portions of the
> > OpenVMS work underlying the undefined file attributes support added for
> > the ODS-3 and ODS-4 ISO-9660:1988 file system support.
> >
> > Making metadata dependencies optional in the higher-level software and
> > in the apps would be very useful, particularly when adopting a plug-in
> > scheme for file system support.  This for kernel support, as well as
> > support for a FUSE-like file system in user space.  Basically, this
> > means that some volumes might be "RMS immune" or "RMS incompatible", in
> > practical terms.  You get a stream of bytes or a stream of sectors and
> > both being sequential organizations, or you can get to use your own
> > record structures on this file system, or you can use an integrated or
> > add-on database package for your storage.
> >
> > A host reading and writing the file system and its metadata must also
> > cause other hosts sharing that storage to manage the local and
> > now-incoherent cache contents appropriately; cache reloading, cache
> > eviction and/or wholesale cache flushing; there must be cache
> > coordination.  While SSD storage is much faster than Hard Disk Drive
> > (HDD) storage, main memory is yet faster still, which means there'll
> > still be interest in I/O caching in main memory.  (A design difference
> > in the existing OpenVMS caching underlies the Shared Stream I/O (SSIO)
> > corruptions, too.
> > http://de.openvms.org/TUD2012/opensource_and_unix_portability.pdf )
> 

With all due respect, RMS data is NOT included in directory entries (reference: the ODS-2 specification OR McCoy sanitized version published by Digital Press). If RMS metadata were stored in the directory, VERIFY/LOST would clearly not be functional.

RMS metadata is split between the file header (for sequential file information), and a combination of the file header and "within the file" data for direct and indexed files.

- Bob Gezelter, http://www.rlgsc.com