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Diffstat (limited to 'RELEASE_NOTES.md')
-rw-r--r-- | RELEASE_NOTES.md | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md index 115a759e..137685d6 100644 --- a/RELEASE_NOTES.md +++ b/RELEASE_NOTES.md @@ -24,6 +24,42 @@ node[:virtualization][:systems][:vmware] = "guest" Due to the requirements for being an LXC host being easily fulfilled, we only populate the old system (role & system) with LXC if there are no other virtualization systems detected. + +### Filesystem2 + +There is a new plugin for filesystems in Linux. It solves several problems: +* Can handle multiple virtual FSes with the same "device" (eg, 'none') +* Can handle a device mounted multiple places +* Is resilient to mtab being a symlink to /proc/mounts +* Provides multiple views for ease of use +* Provides a mechanism that has gauranteed lack of overwritten data +* Forks far fewer times than it's predecessor + +Unlike the 'filesystem' plugin, it provides 3 views into the data: + +* `by_pair` is the primary one and what most users are expected to use. It + gaurantees no loss of data from conflict and has an entry in the hash for each + pair of $device,$mountpoint (or "$device," for unmounted devices). +* `by_device` a similar layout to the original filesystem plugin which is + indexed by device, except that 'mount' entry is now 'mounts' and is an array. + While this solves many of the problems users can encounter by having /etc/mtab + be a symlink to /proc/mounts it can still have data loss due to different + mount options, or multiple virtualfs mounts with the same fake device name. +* `by_mount` similar to the above but indexed by mountpoint. Won't include + unmounted filesystems, of course. + +It is recommended to always use `by_pair` when iterating or wanting a full view +of storage devices. The other two are provided for convenient lookup. Other +notes: + +* The `by_mount` view handles conflicts in a last-wins manner. Other than that, + fields should be the same except for the lack of a "mount" key inside entries + (since that's the key to the structure) +* The `by_device` mount changes the structure slightly to replace 'mount' key in + each structure with 'mounts' - an array of mountpoints instead of overwriting + values. For other conflicts last one wins. 'devices' is not a key inside + entries since it's the key to the structure. + ### Miscellaneous * Ohai now collects mdadm RAID information. |