On Tue, Jun 12, 2007 at 11:46:20PM -0400, John Stoffel wrote: > >>>>> "Chris" == Chris Mason <chris.mason@xxxxxxxxxx> writes: > > Chris> After the last FS summit, I started working on a new filesystem > Chris> that maintains checksums of all file data and metadata. Many > Chris> thanks to Zach Brown for his ideas, and to Dave Chinner for his > Chris> help on benchmarking analysis. > > Chris> The basic list of features looks like this: > > Chris> * Extent based file storage (2^64 max file size) > Chris> * Space efficient packing of small files > Chris> * Space efficient indexed directories > Chris> * Dynamic inode allocation > Chris> * Writable snapshots > Chris> * Subvolumes (separate internal filesystem roots) > Chris> - Object level mirroring and striping > Chris> * Checksums on data and metadata (multiple algorithms available) > Chris> - Strong integration with device mapper for multiple device support > Chris> - Online filesystem check > Chris> * Very fast offline filesystem check > Chris> - Efficient incremental backup and FS mirroring > > So, can you resize a filesystem both bigger and smaller? Or is that > implicit in the Object level mirroring and striping? Growing the FS is just either extending or adding a new extent tree. Shrinking is more complex. The extent trees do have back pointers to the objectids that own the extent, but snapshotting makes that a little non-deterministic. The good news is there are no fixed locations for any of the metadata. So it is at least possible to shrink and pop out arbitrary chunks. > > As a user of Netapps, having quotas (if only for reporting purposes) > and some way to migrate non-used files to slower/cheaper storage would > be great. So far, I'm not planning quotas beyond the subvolume level. > > Ie. being able to setup two pools, one being RAID6, the other being > RAID1, where all currently accessed files are in the RAID1 setup, but > if un-used get migrated to the RAID6 area. HSM in general is definitely interesting. I'm afraid it is a long ways off, but it could be integrated into the scrubber that wanders the trees in the background. -chris - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
