[Info-vax] FTP FYI

[Stephen Hoffman]

On 2020-11-23 21:00:24 +0000, Phillip Helbig (undress to reply said:

> In article <rpgvdq$bgp$1 at dont-email.me>, Stephen Hoffman
> <seaohveh at hoffmanlabs.invalid> writes:
> 
>> However...  Updates to BACKUP seem nonsensical longer term, as the 
>> current app design is close enough to its performance limits to not  
>> matter.
> 
> Is there any reason not to use ZIP?

Other than that it doesn't address the performance issues, and lacks 
support for aliases as are routinely used on OpenVMS system disks, no.

To use zip here, zip would need updates including a call to the 
SETBOOTSHR API, the addition of support for aliases, and likely a few 
other details.

And when last I checked, there was no way within the zip archive layout 
to have multiple file entries pointing to one hunk of file data, which 
means zip would capture a lot of extra data on a system disk. BACKUP 
has alias support.

> It not only makes an archive, but  it is much faster to extract 
> individual files from it, it also does  compression, and is very 
> portable should one need to transfer files  between different operating 
> systems.  For a while now it can handle large files and/or large 
> archives.

I prefer zip to BACKUP for most uses, too.

I'd tried getting zip and unzip into the distro. Maybe VSI succeeds.

BACKUP offers compression, and also offers robust encryption. zip 
provides compression by default, though lacks robust encryption support.

It wouldn't surprise to learn that both zip and BACKUP use older and 
less efficient compression, but I've not verified that.

nb: always remember to compress before you encrypt. This as there's no 
point to even try compressing encrypted data.

> For really large savesets, is there something BACKUP can do but ZIP 
> can't?  Is BACKUP faster than ZIP (assuming no compression)?

BACKUP and zip share the underlying I/O issues here. You can't get 
faster than the underlying storage speed with the whole-device strategy 
used by BACKUP. Which here mirrors that used by zip.  Incremental 
backups such as can be used with BACKUP aren't a particularly good 
alternative to file system change notifications, either.


-- 
Pure Personal Opinion | HoffmanLabs LLC