[Info-vax] VMS to VMS data copy options/performance when losing a DECnet link

[Bob Gezelter]

On Friday, April 8, 2022 at 11:30:49 AM UTC-4, Rich Jordan wrote:
> On Friday, April 8, 2022 at 6:24:37 AM UTC-5, geze... at rlgsc.com wrote: 
> > On Thursday, April 7, 2022 at 7:24:03 PM UTC-4, Rich Jordan wrote: 
> > > Customer has decided to turn off "legacy" DECnet support on their network. They currently use DECnet for copies between two nonclustered integrity servers that are on different IP subnets/VLANs and have Cisco doing whatever magic it does to make DECnet appear local. THis is Phase IV, not DECnet over IP. 
> > > 
> > > Is there any documentation on relative performance for bulk data transfer with preliminary data archiving (ie ZIP or backup to a local archive file so not transferring lots of individual files) on VMS using FTP/SFTP versus using NFS as the transfer mechanism? I know details matter and I don't have them yet but is one likely to be enough different that it is worth pursuing a test? Which won't be trivial given equipment availability... 
> > > 
> > > Thanks for any info 
> > Rich, 
> > 
> > As Robert noted, DECnet Phase V over IP is a viable choice. In situations where the client did not want to do that change, I have used sftp quite effectively, often in concert with ZIP/UNZIP. 
> > 
> > As an example, in one quick test, I was able to transfer more than a terabyte of data in a reasonable time (I do not have the precise numbers in easy reach at the moment). The context was non-tape backup. The process was: 
> > - Do BACKUP/IMAGE to a scratch device 
> > - use ZIP "-V" to compress the BACKUP save set. Your mileage will vary, I was able to get approximately 90% size reduction. 
> > - Use sftp to copy the resulting ZIP files to the destination machine 
> > - UNZIP the transferred files 
> > - use BACKUP to restore the saveset on the destination machine 
> > 
> > The above was run in multiple BATCH jobs on both sides. 
> > 
> > - Bob Gezelter, http://www.rlgsc.com
> Thank you all for responses. I'm not excited about the thought of installing Phase V mainly because it has been 25+ years since I even looked at it. I can see if it is an option. At least that I can test here at our office. 
> 
> Losing current DECnet transit is not negotiable apparently; we lost that argument but that choice is with the customer and their network vendor/support; we and the VMS boxes are a side issue that just needs to deal with the change. 
> 
> As noted we already do some data moves by doing backup to local disk savesets (using the /DATA_FORMAT=COMPRESS option) then FTP'ing those sets to a PC. Fully tested so we know we can retrieve those savesets, fix the attributes, and restore them because doing even a zero compression encapsulating ZIP takes too much time for the larger savesets (ZIP would preserve the backup saveset file attributes). 
> 
> The current VMS to VMS is done with DECnet copies of individual files, or backup of folders/trees or bulk files to remote saveset via DECnet that gets restored on the remote system.
Rich,

If you are transferring trees or subtrees, the /IMAGE is completely unnecessary.

The reason I used ZIP was to preserve the OpenVMS file attributes when transferring. OpenVMS ZIP/UNZIP can preserve file attributes without problem.

How large are the data volumes being transferred.

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