Messages in this thread | | | Date | Wed, 17 Dec 2008 16:30:00 -0500 | From | Jeff Garzik <> | Subject | Re: Notes on support for multiple devices for a single filesystem |
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Andreas Dilger wrote: > I can't speak for btrfs, but I don't think multiple device access from > the filesystem is a "layering violation" as some people comment. It is > just a different type of layering. With ZFS there is a distinct layer > that is handling the allocation, redundancy, and transactions (SPA, DMU) > that is exporting an object interface, and the filesystem (ZPL, or future > versions of Lustre) is built on top of that object interface.
Furthermore... think about object-based storage filesystems. They will need to directly issue SCSI commands to storage devices. Call it a layering violation if you will, but you simply cannot even pretend that an OSD is a linear block device for the purposes of our existing block layer.
Jeff
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