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FILE_SYSTEMS_REISING
February 19, 2017
Hans Reiser wrote software: he
developed one of the first I've never gotten a good feel for
serious file systems for Linux, why Reiser4 was never adopted into
"Reiser3" and was working on a linux core: as I remember it, Linus
follow-on project "Reiser4" that Torvalds was complaining that
was never really accepted by the Reiser wouldn't modify his code to
linux developers. comply with linux standards... it
sounded to me like some sort of
I've always liked Resier3, and social breakdown. Hans Reiser
regret that it seems to be could certainly be pretty crazy,
becoming a second-class citizen and Linux Torvalds can be pretty
in the linux world: there are a cantankerous himself...
number of file systems available
now that are designed to scale
upwards to deal with very large LINUX_REISING
files, but Reiser FS (and Reiser
FS alone, as far as I know) was
designed to scale down to cover
the case of large numbers of
small files.
That fits in well with the
way some classic unix
software works e.g. email
servers, or (a personal
favorite) the "mh"-style
mail client software. There are a number of odd hacks
that are suprisingly common
Most of us are somewhat aware of where a system administrator
the limitations of our filesystems, will decide to alphabetize a
and have gotten used to dancing large set of files, and move
around them: if you tried to them into sub-directories named
architect software to use lots of for each letter. That's
small files these days you'd find evidently a performance win for
someone intoning "don't treat the many systems... but why would
file system like a database!". anyone put up with having to do
this kind of work manually?
Hans Reiser (and again, Hans
Reiser alone as far as I (On the old Stanford TOPS-20
know) decided that the file systems, everyone's usernames had
system should *be* a an odd structure to them like
database, and went after "J.JBRENNER", i.e. "JBRENNER" in
those restrictions. the subdirectory "J".)
He published a paper on Consider the "mbox" file
the subject of "namespace format (popularized by
unification", which tells the Berkeley "mail" program)
you a lot about the thinking which stores a large
that underlied Reiser4... stash of many mail messages
glued together into one
Note: he named his file. That's no doubt more
company "NameSys". "efficient" in many respects,
but why should a programmer
be forced to work that way?
Isn't it reasonably natural
to think in terms of one
file per message (and one
directory per mail folder,
and there you have the old
"mh" approach).
From Wired magazine, 2006.
http://www.wired.com/wired/issue/15-07
Joshua Davies:
"Reiser4 is built on this principle. It contains
a single registry-- known as a balanced tree-- The use of the term
to organize every piece of data in the operating "balanced tree" here
system. All programs can employ the same is just enough off
nomenclature to access information. In the to make it clear that
traditional Windows or Unix file system, each Davies isn't a
application uses different terminology to track programmer.
data. As a result, programs don't communicate
efficiently with one another, which creates The registry isn't
walls between data. In Reiser's idealized a balanced tree...
vision, a simple search for the word 'Nina,' for we might say it's
instance, will turn up emails in Outlook, images keys are arranged
stored in MyPictures, and credit card charges in in a balanced tree,
Quicken. Google's desktop search and Apple's or that the index
Spotlight feature can do this, but they're is a balanced tree,
afterthoughts: The ability of Reiser4 to scour or something like
every document is embedded in the operating that.
system itself. It lays the foundation for a
digital universe where there is no But then, just
discrimination-- nothing is walled off. In this calling it a
unified space, all things can be known." "registry" is
a little tone
Obvious question: deaf: it reminds
"Security?" of the windows
registry--
One would hope widely regarded
they thought as a disaster by
about it. unix people
This use of language is everywhere, who
essentially a matter of prefer files
social flags, however of "plain text",
much we might want to (whatever that's
pretend it's a matter of supposed to be).
technical understanding.
For all I know, Davies may
understand the *idea* of
balanced trees very well.
(Perhaps better than I do: my
understanding of such topics is vague
unless I feel a need to dive into
them, and typically I don't: I don't
claim to have a CS background, and
make no apologies for not thinking
like someone who does.)
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