From: Bill Todd [billtodd@foo.mv.com]
Sent: Sunday, July 11, 1999 1:37 PM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: Whither VMS?

Dave's point below was the reason for 'clustering' child file-headers in
item 4 of the list.  The NTFS practice of including the information in the
directory is a real pain when you start distributing directory information
around a cluster:  the directory pages get invalidated all the time, like
whenever a file access date of EOF changes.  Grouping the child file (but
not sub-directory) headers such that a bunch can be read in one disk
revolution gives good directory-list performance (including the per-file
data) for directories of reasonable size, while not impacting normal path
look-ups.  There's a bit of extra house-keeping in tracking free space in
the groups, but having that information in the directory itself rather than
having to allocate from the index file bit-map each time may actually speed
up processing, since you have to write the directory block anyway when
allocating/deallocating a file.  All in all, it's the best trade-off I could
come up with.

- bill

Dave Pickles <davep@nugate.demon.co.uk> wrote in message
news:931680368.64376415@localnews...
7. As a big-time PathWorks user, do whatever it takes to bring performance
up
to par with M$ offerings. I'm no expert on the details, but the present
arrangement where file details are held in INDEXF.SYS with only the
filenames
in the directories must slow down directory lookups (especially when the
client
machine needs file size and access control information presently held in
ACLs).

Incidentally I'm surprised that the disaster-tolerance of PathWorks on a VMS
cluster isn't more widely advertised (ie in the PC magazines). I only knew
it
existed because we already had a VMS installation.

Imagine the TV ad: camera tracks along a row of workers typing on their PCs
or
working with rotating 3D CAD models, all totally immersed in their work. The
door at the end of the room opens and an Arnie lookalike enters carrying a
huge
axe, he walks past the workers (still engrossed in their tasks) and stops in
front of a pair of servers bearing the VMS logo. He swings his axe and
destroys
one of the servers (cue sound fx of dying server, go easy on the smoke and
flames!) then walks back. We see the workers continuing exactly as before.
The
copy I'll leave to the ad agencies; there could perhaps be a follow-up ad
showing what would happen to an NT server!

--
Dave Pickles