9.1 Proposal: shutdown menu

pgf at laptop.org pgf at laptop.org
Wed Oct 22 15:43:52 EDT 2008

i wrote:
 > michael wrote:
 >  > On Wed, Oct 22, 2008 at 10:54:52AM -0400, pgf at laptop.org wrote:
 >  > >this feature has been discussed on the list(s) earlier, but i'm not
 >  > >sure of its status.  i'd like to make sure it gets on the table.
 >  > >(and it just came up in dan's ethiopian report.)
 >  > >
 >  > >currently it is much easier to "crash" the laptop (by holding the
 >  > >power button down) than it is to shut it down cleanly.  while the
 >  > >journalled filesystem (currently) can recover from this on the
 >  > >next boot, application writes in progress might not.
 >  > 
 >  > (for the record)
 >  > 
 >  > I'd be much more interested in proposals for how (socially) to get more
 >  > activities using ACID storage.
 > since the first page of google hits is all about where to 
 > keep batteries and juvenile diseases, i need to ask you
 > for a link.  :-)

thanks for the links folks.
    "In computer science, ACID (Atomicity, Consistency, Isolation,
    Durability) is a set of properties that guarantee that database
    transactions are processed reliably."

that's a great idea.  i'm all for it, and i like apple pie, too.

but it's sort of orthogonal to dealing with existing applications
that haven't been properly socialized to new ways.

existing programs will continue to buffer output that won't get
written if the system crashes, and hold filesystem locks that may
still exist on reboot, etc.  they'll leave dangling tcp streams,
and their peers won't know they've disappeared.  it's just poor
hygiene to not shut down cleanly.

and, while jffs2 and our current NAND seem to do a good job of
staying consistent after an unexpected reboot, we've been doing
lots of work on replacing one or both.  new filesystems will probably
be robust in that way, but LBA-NAND or SD might not be.  (i can
say from experience that compact flash most definitely is _not_
robust in that way.)

 paul fox, pgf at laptop.org

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