What compression scheme generates smallest ISO snapshot?

[Member rayluo]

The official antiX-19.3_x64-full.iso size is 1164 MB. I added chrome into it, and then created my own snapshot using the xz compression scheme, and got an outcome of even smaller-than-official ISO size: 1095 MB. In other words, I do not know what compression scheme was used to create the official 19.3-x64-full ISO, but it seems less compact than xz. In fact, I tried all 4 options in the ISO snapshot tool before, and xz generates the smallest ISO.

Out of curiosity, I wonder if I could use same technique to get a smaller 19.3-386-base ISO, and potentially get it back to a CD size. But this time the result is the opposite. The official antiX-19.3_386-base.iso size is 752 MB. I did NOT add any thing (except upgrading the iso-snapshot-antix and iso-template-antix), and created a snapshot using xz, but the outcome 775 MB is bigger than the original. Why so? Was the original base iso already built with yet another compression scheme with even higher compression ratio? If so, why isn’t that scheme not available in ISO Snapshot tool?

Reference: The compression benchmark of the 4 schemes currently provided by ISO snapshot tool: lz4, lzo, gzip, xz
https://catchchallenger.first-world.info/wiki/Quick_Benchmark:_Gzip_vs_Bzip2_vs_LZMA_vs_XZ_vs_LZ4_vs_LZO

UPDATE Note: I removed the mentioning of Chrome in the post above. It simply caused misunderstanding. (That outcome of a larger 19.3-386-base ISO did **NOT** contain a chrome.)

[Anonymous]

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> I tried all 4 options in the ISO snapshot tool

further permutations are possible.
For example, with gz or xz, you can specify “level=” [0-9]
If level= is not explicitly specified, IIRC the default level applied is “6”

another benchmarking article: gzip-vs-bzip2-vs-xz-performance-comparison/ ./a> .

> antiX-19.3_386-base.iso size is 752 MB. I did NOT add anything
> (except upgrading the iso-snapshot-antix and iso-template-antix),
> and created a snapshot using xz, but the outcome (775 MB) is bigger than the original. Why so?

it is probably primarily due to
> I added chrome into it, and

no one using chrome(ium) has contributed a pattern (“home/*/.cache/chromestuffhere”)
or list of patterns for excluding chrome-related cache//junk files
iso-snapshot-exclude.list
After tracking down the relevant paths, you might consider posting a list in the forum and/or in a gitlab.com/antiX-Linux/iso-snapshot pull request.

To recreate the scenario, you can:
liveboot the pristine iso, setup dynamic root persistence, perform chrome install (and repeat whatever other actions) perform the snapshot operation, then persist-save, shutdown, reboot…

In the subsequent session, mount the rootfs and inspect its content(s), ala

sudo mkdir -p /mnt/shadowrootfs
mount -t ext4 /live/boot-dev/antiX/rootfs /mnt/shadowrootfs -o loop,user,ro,noexec
find /mnt/shadowrootfs * >> /tmp/MyRootfsManifest.txt

[Anonymous]

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^—- not a product poor reading comprehension, just poor memory
(I had clicked post expecting to PREVIEW and proofread, forgetting that this forum lacks a preview feature.)

I hear ya ~~ chrome was not involved during the “386” run

> Was the original base iso already built with yet another compression scheme with even higher compression ratio?

compression method has been discussed//debated repeatedly in forum posts, especially in the release betatesting threads. I haven’t read that detail for 19.3 release, but prior recent releases have probably employed lz4 compression (that was the concensus agreed during betatesting)

[Anonymous]

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> 19.3-386-base ISO, and potentially get it back to a CD size

Toward that goal, I tested

sudo apt update
sudo bash -c 'echo "en_US.UTF-8 UTF-8" > /etc/locale.gen'
sudo dpkg-reconfigure locales -p high
sudo apt install localepurge
sudo apt dist-upgrade
sudo apt install bleachbit
sudo bleachbit -c system.localizations
sudo apt purge bleachbit

That quick pass, with xz compression, yielded a 721MB snapshot ISO file.

For “pass number two”, I would suggest:

sudo apt install synaptic
### launch synaptic, search “firmware” and remove the stuff inapplicable to your system(s)
###____for instance, if not using wifi…
###____purging the firmware-iwlwifi package would free 89.1MB
###
### visit synaptic toolbar “Settings” and, in “Preferences}}Columns-n-Fonts”
### move up (leftward) the “Size” column, then Apply, Ok
###
### Left-bottom pane, click “Status” then in top-left “Installed”
### and click (dblclick) to toggle sorted view, by Size.
### Decide which largish items you might want to cull and
### after UNshopping, you can optionally purge synaptic (15MB)

browse /usr/share/wallpaper/
and cull (prettyPink?) any large imgfiles you will not use

optional (1.5MB files on disk)
sudo rm /usr/share/perl/5.28.1/Collate/Locale/*
sudo rm /usr/share/perl/5.28.1/Collate/CJK/*

[Anonymous]

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> further permutations are possible.

mksq_opt=
within iso-snapshot.conf file
YMMV. See related discussions here: https://forum.mxlinux.org/search.php?keywords=mksq_opt

[Member catfood]

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Broad assumption here, but the antiX live is a bit bloated, it has ALL the firmware it can hold on an older kernel to allow it all. A remaster after the installer finds its target architecture, is likely to shave half the initial live requirements and ” MTUNE=Intel or AMD”. It’s designed to be leaner when possible. I believe Dolphin has a few videos too going further in depth about antiX live saving hardware profiles, so when you go from desk to lap, etc, it knows one needs wifi or not, etc. Hardware tuned kernel will run faster than a boot on everything kernel…

Also, when you remaster, it gives you a few various compression formats. Yes some are half the size, but as the notes even say, some formats will reload and boot way faster. I’d guess the antiX live iso is tuned towards medium or speed, vs. size. A lower remaster could just be choosing a smaller zip choice.

• This reply was modified 2 years, 5 months ago by catfood.

Howdy Jessie.

[Member rayluo]

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Thanks @skidoo for trying to help! 🙂 I modified my original post to remove the mentioning of Chrome. It was confusing and misleading. What I meant to say was indeed “a live boot, pristine 19.3-386-base ISO, WITHOUT adding extra software, ended up becoming a larger ISO than what we can download from official website”.

Your command line samples are definitely intriguing. I might try it the other day. This post was largely a brainstorming attempt, perhaps more for AntiCapitalista. 😉 Personally I use antiX-full ISO which has long been passed that 711MB mark. 🙂

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