emonSD image compression


I’ve recently noticed the xz offers much better compression for emonSD images. For those of us using linux, it would be nice to download a single emonSD.img.xz file (829 MB) instead of a single-file zip (1.2 GB).

I don’t know if windows users can open xz files. It’s basically just LZMA2, so I would expect so.


Another good example of Google is your friend.


Three popular Windows archive apps - WinRAR, WinZip and 7zip - can handle xz compressed files.

From a Google search

From the WinRAR page:

There’s one big benefit of “zip” files… Everyone knows what to do with a .zip file.
You give someone a “.xz” file and their first reaction is going to be “What the?”

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True, but then

is a fair incentive to find out, unless you have a greased lightning BB service.

How often are individuals downloading EmonSD images that the extra ~300MB is causing significant issues/delays?

One could equally suggest that we should use .rar (1993), or .7z (1999) or any number of other compression formats that have been around longer than .xz (2009), are more widely known and likewise offer better compression than .zip.

I’m just playing devils advocate here, I really don’t have a stake in this :slight_smile:. The difference of 300+ MB to me is about 5 extra minutes download time, but if OEM are paying for hosting bandwidth, maybe looking at the compression method of the image is worth their effort?

While were talking about bandwidth and downloads of the image, has anyone from OEM thought about putting up a torrent tracker and creating a torrent file for the image? The rest of the community could assist in hosting the image - I’d certainly be happy to seed it.

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But it’s still 300 MB on my data quota that’s unnecessary.

Yep, one wouldn’t have to to that too many times to eat a sizable chunk out of a 10 GB quota.
Not to mention any other file transfers, etc…

Heading slightly off-topic now… Surely that’s a mobile phone data plan??? Is anyone actually downloading an emonSD image using their mobile data plan? Flipping that around, how many people with home internet are on a 10GB monthly quota? Here in Australia, 100GB is the smallest, with many providers offering “Unlimited” as their standard offer for home Internet (ADSL or VDSL)

Not a mobile plan, but a metered home inet plan with a 10GB limit.

Yes, I understood it was metered… my question still stands… who has a 10GB metered home plan?
I’m fairly used to seeing mobile (or cell if you like) data plans around 10GB… is that what we’re talking about?

How prevalent is that for people downloading an emonSD image?

Robert does…

… and I thought Australia had backwards Internet!

I’ve just had a look at the “compressed image” support in Etcher and it has had built-in support for .xz files since v1.0.0 (> 2 years ago)

Given the emonSD “Download and Flash” instructions suggest using Etcher to push the image onto your SD card, perhaps .xz is actually the most appropriate compression format :smiley:

I’d simply offer both - job done.

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Always with the simple solutions… :yum:

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