From: hoffman@xdelta.zko.dec.nospam Sent: Wednesday, June 21, 2000 11:23 AM To: Info-VAX@Mvb.Saic.Com Subject: Re: Storage Works / Snapshots / Maybe it's time to skip OpenVMS In article <8iocob$kqg$1@nnrp1.deja.com>, d.webb@mdx.ac.uk writes: :There was going to a product to do precisely this - snapshot services. :Unfortunately it was cancelled on VMS. More specifically: unfortunately, Snapshot Services was found to be lacking features and capabilities expected by OpenVMS users and was cancelled on OpenVMS. :It sounded so great... :Stop your applications for a second. Take a snapshot of your disks. :Continue on. Backup your snapshots. .. :If I recall correctly the software was produced for NT - then the VMS :version got canned. The design of Snapshot Services was found to function nicely for typical Windows NT environments, but was also found to not scale to the numbers of disks and to the typical installation scale expected by OpenVMS users, nor did the design particularly operate in shared-everything clustering environments expected of and common on OpenVMS. :We were promised that the functionality would be rolled into the future :improvements in shadowing etc. Mini-copy and mini-merge shadowing uses some of the concepts behind Snapshot Services, and these are included in OpenVMS V7.3. The new XFC file caching support first appears in V7.3, as well. While the write-behind caching support is not yet included -- though the implementation is proceeding nicely -- I would expect to see various enhancements to the XFC base in future releases after V7.3. :So anyone - Will the new file system work etc in VMS 7.3 include :snapshot services ? There is no work going on for support of Snapshot Services. The current work on a new file system will be included in a release after V7.3 -- this work is intended to eliminate some of the basic limits in the design of both ODS-2 and ODS-5. We will be continuing work for faster backups and for better support of on-line backups, and we have support in V7.3 and are continuing to add new support (eg: quiescence locking) in upcoming OpenVMS releases. Alternatives and enhancements to the current BACKUP design are also under investigation, as we are reaching the theoretical maximum for the current design. --------------------------- pure personal opinion --------------------------- Hoff (Stephen) Hoffman OpenVMS Engineering hoffman#xdelta.zko.dec.com