NILFS2, a log-structured filesystem

[Célio Cidral Junior-2]

I guess this new fs is perfect for prevayler journal.

-----
NILFS2 is a new filesystem which uses a log-structured design. What
makes log-structured filesystems different is that they treat the
whole disk as a consecutive list of blocks (called log). All the
operations append data at the end of the log, they never rewrite
blocks (except when there's no space left - in that case, new blocks
are reclaimed from the start of the log). The advantage of this
approach is that all modifications and creations are converted into
sequential operations, which are faster. Crashes can't corrupt the
filesystem. On mount, the filesystem detects the real end of the log,
and continues working from that point.

Another advantage of this approach is that the log offers a coherent
historical view of all the operations done in the disk in the past.
This is called "continuous snapshotting" - snapshots of modifications
done in all the filesystem at any time are created automatically due
to the log-structure design, with no requirement of intervention from
an admin, and with the filesystem size as the only limit. NILFS2
allows to access those snapshots and even mount them (on read-only
mode).

NILFS2 is under development. Code: fs/nilfs2/. Filesystem web page:
www.nilfs.org

Text taken from http://kernelnewbies.org/Linux_2_6_30

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[Klaus Wuestefeld]

Very interesting.

> This is called "continuous snapshotting" - snapshots of modifications
> done in all the filesystem at any time are created automatically due
> to the log-structure design

What does this mean? Could you explain this better?

Klaus.


2009/6/15 Célio Cidral Junior <ccidral.dev@...>:

> I guess this new fs is perfect for prevayler journal.
>
> -----
> NILFS2 is a new filesystem which uses a log-structured design. What
> makes log-structured filesystems different is that they treat the
> whole disk as a consecutive list of blocks (called log). All the
> operations append data at the end of the log, they never rewrite
> blocks (except when there's no space left - in that case, new blocks
> are reclaimed from the start of the log). The advantage of this
> approach is that all modifications and creations are converted into
> sequential operations, which are faster. Crashes can't corrupt the
> filesystem. On mount, the filesystem detects the real end of the log,
> and continues working from that point.
>
> Another advantage of this approach is that the log offers a coherent
> historical view of all the operations done in the disk in the past.
> This is called "continuous snapshotting" - snapshots of modifications
> done in all the filesystem at any time are created automatically due
> to the log-structure design, with no requirement of intervention from
> an admin, and with the filesystem size as the only limit. NILFS2
> allows to access those snapshots and even mount them (on read-only
> mode).
>
> NILFS2 is under development. Code: fs/nilfs2/. Filesystem web page:
> www.nilfs.org
>
> Text taken from http://kernelnewbies.org/Linux_2_6_30
>
> ------------------------------------------------------------------------------
> Crystal Reports - New Free Runtime and 30 Day Trial
> Check out the new simplified licensing option that enables unlimited
> royalty-free distribution of the report engine for externally facing
> server and web deployment.
> http://p.sf.net/sfu/businessobjects
> _______________________________________________
> To unsubscribe go to the end of this page: http://lists.sourceforge.net/lists/listinfo/prevayler-discussion
> _______________________________________________
> "Databases in Memoriam" -- http://www.prevayler.org
>

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[Célio Cidral Junior-2]

2009/6/15 Klaus Wuestefeld <klauswuestefeld@...>:
>> This is called "continuous snapshotting" - snapshots of modifications
>> done in all the filesystem at any time are created automatically due
>> to the log-structure design
>
> What does this mean? Could you explain this better?

Not sure I got it right, but I think it means that each change (or set
of changes) in the FS generates a snapshot of its current state.
Seems to me like revisions in an svn repository, if this analogy makes
sense.

Celio.

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