File:  [NetBSD Developer Wiki] / wikisrc / projects / project / tmpfs-snapshot.mdwn
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Sun Nov 6 21:08:23 2011 UTC (2 years, 5 months ago) by jmmv
Branches: MAIN
CVS tags: HEAD
Add missing categories to the "all" index and sprinkle difficulty-level
settings to the projects that lacked them.  The "all" index is now fully
organized.

[[!template id=project

title="Add snapshots to tmpfs"

contact="""
[tech-kern](mailto:tech-kern@NetBSD.org)
"""

category="filesystems"
difficulty="medium"

description="""
Add memory-efficient snapshots to tmpfs.  A snapshot is a view of the
filesystem, frozen at a particular point in time.  The snapshotted filesystem is
not frozen, only the view is.  That is, you can continue to
read/write/create/delete files in the snapshotted filesystem.

The interface to snapshots may resemble the interface to null mounts, e.g.,
'mount -t snapshot /var/db /db-snapshot' makes a snapshot of /var/db/ at
/db-snapshot/.

You should exploit features of the virtual memory system like copy-on-write
memory pages to lazily make copies of files that appear both in a live tmpfs and
a snapshot.  This will help conserve memory.
"""
]]

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