Re: Final CDs being written for Stretch - 9.13 release - prior to LTS

[Andrew Cater <amacater@gmail.com>]

Streaming production of .iso files _is_ technically possible. Jigdo effectively builds the iso file from chunks of ten or so files until the disk is complete and checksummed. As mentioned, this query was about stopping production of the .iso files specifically meant for the oldestMac mini. That certainly sounds possible for Bullseye when it gets here since that particular model will be about 15 years old and there's likely to be very few of them still running.

I'm collecting what people are sending me on and off list. It does seem that we may be able to stop routine production of as many images. Netinst, something DVD-ish sized (so smaller than 8G) and some (larger file size ??) may do it. The problem of using http to download large files is that it's fairly difficult on a slow link or one which is losing packets. Jigdo does work well to build .iso images - it might need more documentation.

Hope this helps

On Mon, Jul 20, 2020 at 2:25 PM Stefan Monnier <monnier@iro.umontreal.ca> wrote:

>> An alternative is to have "virtual ISO images", i.e. images which are
>> constructed on the fly (presumably by jigdo) on the web-server side.
> Assuming that a complete set of ISOs for whatever medium occupies
> at most 100 GB, it seems better to have the images ready rather than to
> assemble them on demand, even if the mirror latency and bandwidth are
> no problem.
> This would spare the nightmare of managing the life cycle of temporary ISOs
> on the server. I assume that all images would fit on a single modern HDD.

I was thinking of a scheme by which the ISO is constructed and streamed
at the same time, so the complete ISO images aren't ever stored whole
anywhere on the server.

> But the reason for letting the user perform jigdo download is that the network
> load vanishes in the normal traffic of the package servers. If download gets
> interrupted, one just has to start it again to get the remaining work
> completed.

Very good point.  I did not consider the interrupt&restart issue.

> The production of jigdo files is a linear effort only if the producer
> knows where the filesystem stores file content data. This knowledge is in
> the ISO 9660 producers genisoimage and xorriso. For other filesystems
> the matching jigdo producer software is not available yet.

I'm not sure I understand what this means, but it does sound like it
implies that streaming production of ISOs is technically possible.


        Stefan