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 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