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 Forum index » Taking the Puppy out for a walk » Misc
Junjiro R. Okajima
Moderators: Flash, JohnMurga
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jamesbond

Joined: 26 Feb 2007
Posts: 1875
Location: The Blue Marble

PostPosted: Sun 20 Mar 2011, 03:36    Post subject:  Junjiro R. Okajima
Subject description: Author of aufs
 

In the wake of the recent earthquake and tsuname in Japan, does anybody know whether he is ok?

Information from google is scarce ... in fact, non-existent. I don't think he visits puppy forum, but anybody who happens to know him or has his contact ... I just saw this in Slax http://www.slax.org/aufs.php, and I sincerely hope that the disaster doesn't make it worse.

cheers!

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jamesbond

Joined: 26 Feb 2007
Posts: 1875
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PostPosted: Mon 21 Mar 2011, 00:30    Post subject:  

Hmmm ... lots of reads, but no response. For those who don't know, slax is not the only distro that depends on aufs ... puppy also depends on aufs.
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Flash
Official Dog Handler


Joined: 04 May 2005
Posts: 10656
Location: Arizona USA

PostPosted: Mon 21 Mar 2011, 00:49    Post subject:  

Since you brought it up, this might be a good time and place for a short description of aufs. What is it and how does Puppy use it?
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jamesbond

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PostPosted: Mon 21 Mar 2011, 02:44    Post subject:  

Aufs ("another union fs") is a kernel module that enables multiple filesystems to be stacked/layered and combined on top of each other.

From practical point of view, this is what enables puppy's versatile mode of operation: multisession dvd, frugal install, usb flash.

For example, in multisession dvd, we have (at least) two layers: bottom layer is read-only pup.sfs on dvd, and the top layer is a RAM filesystem (more if you have saved sessions and/or use other SFS-es). Aufs combines these two layers into one coherent view - you see one filesystem containing both the content of pup.sfs and RAM, and it also enables you to write / change the content of files which exist on pup.sfs (the file isn't actually changed on pup.sfs, because it's read only, but instead a new file with the same name is created and modified on the upper RAM filesystem layer, and the presence of this new file will hide the original file on pup.sfs). Thus all new/modified files are collected in RAM, which at the end of the session, you can collect and write back as a new dvd session. We have similar story with frugal install and usb flash.

Can puppy run without aufs? Yes, of course, this is how puppy 1.x did it (as I understand it - I don't have direct experience with puppy 1.x series). In those days, different filesystems are mounted in different directories. You have to know which directory that is writable, and which ones aren't, and only store our files there. It's the reason we have my-application folder in /root, because /root was one of the very few folders which were writable on puppy 1.x (/usr, the typical location for apps, was read only). Now fast forward to today. For the better or worse, today you can write everywhere in the filesystem, install apps, update system files - and the changes will be saved - thanks to aufs.

Aufs is not the only unionfs (that's why the name starts with "another"), there is another one that Barry used to use also, called simply unionfs. Aufs has been preferred and used since puppy 4.x because it's more stable.

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kirk

Joined: 11 Nov 2005
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PostPosted: Mon 21 Mar 2011, 08:57    Post subject:  

He's OK. Here's what he posted on the mailing list:

Quote:
Thank you for the mails.
I am in my apartment and back to aufs now.
My home town Tokio has still problems about the electric power
shortage. But it is definitly minor than people's life in north.

I believe that people returning to what they used to be, for me the aufs
project for instance, helps the reconstruction of this country and
people.

Your mails encouraged me.
Thanks again.

J. R. Okajima
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Flash
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Joined: 04 May 2005
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PostPosted: Mon 21 Mar 2011, 09:25    Post subject:  

Jamesbond, thank you very much for that explanation, and Kirk, thank you for the update. I'm glad Junjiro is ok.

This may not have anything to do directly with aufs, but the order in which multisession Puppy boots puzzles me. It loads the last saved session into RAM first, then the next-to-last, etc., until at the end it finally loads the main sfs for that version of Puppy. I guess it doesn't matter which order the saved sessions are loaded if aufs can combine them all at the end. It just seems like loading everything in the order it was created would be more efficient. For one thing, the DVD reader must continually move back along the spiral to get to the beginning of the preceding file. Surely that slows down the boot process. Is there a reason this boot order must be followed?
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`f00


Joined: 06 Nov 2008
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PostPosted: Mon 21 Mar 2011, 10:17    Post subject: not very technical but
Subject description: a sort of spiritual poetry
 

.. is what I imagine the aufs to be doing in it's dive down through the most recent and orders of layers to the final base, noting in passing the changes made, going back to a proven bedrock that has been built upon (the seed of the pearl as it were) and rising through the nacre to the present glow.

Unless (of course) there's a kernel panic shark in the water.

Diving can be anytime, first is to breathe (for us all)
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jamesbond

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PostPosted: Tue 22 Mar 2011, 04:57    Post subject:  

Flash wrote:
Jamesbond, thank you very much for that explanation, and Kirk, thank you for the update. I'm glad Junjiro is ok.
Very glad to hear he's okay, too. Maybe now everyone's clear of how important his role to puppy is, they may consider that petition on Slax website ...

Quote:
This may not have anything to do directly with aufs, but the order in which multisession Puppy boots puzzles me. It loads the last saved session into RAM first, then the next-to-last, etc., until at the end it finally loads the main sfs for that version of Puppy. I guess it doesn't matter which order the saved sessions are loaded if aufs can combine them all at the end. It just seems like loading everything in the order it was created would be more efficient. For one thing, the DVD reader must continually move back along the spiral to get to the beginning of the preceding file. Surely that slows down the boot process. Is there a reason this boot order must be followed?
Looking at the code, there isn't any particular reason why this has to be so. The order is based strictly on (reversed) directory list order, and the code that does the copying does guard against copying over older files over newer ones. So, in theory at least, one can load the files in any order - including first-to-last. You can suggest this to Barry - the relevant code is
Code:
  BKFOLDERS="`ls -1 -r $CDMNTPT | grep '^20[0-9][0-9]'`"
in /init, inside initrd.gz. In Wary 5.1.1, this is line 1125. The "-r" there makes reverse order (ie last-to-first, because folder names are sorted alphabetically). To make it load first-to-last, just drop that "-r" and make the code to
Code:
  BKFOLDERS="`ls -1 $CDMNTPT | grep '^20[0-9][0-9]'`"

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Lobster
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Joined: 04 May 2005
Posts: 15117
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PostPosted: Tue 22 Mar 2011, 05:21    Post subject:  

Quote:
Thank you for the mails.
I am in my apartment and back to aufs now.

Good news, he understands english, so no need to use my
practically non existent Japanese (mostly from Karate and Judo)
- unless you need a quick kin geri

anyway here is his email address and the email I sent
on everyone's behalf

okajima at digitalinfra.co.jp

Quote:
Hi, Konnichiwa

You don't know me
but people on the Puppy Linux forum were
concerned about your safety
http://www.murga-linux.com/puppy/viewtopic.php?p=505846#505846

As official crustacean for Puppy (an honorary title) I would just
like to express thanks and gratitude for your well being
and efforts

Live Long and Prosper

Ed Jason aka Lobster

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