zfs code - Jul 2009 - RAIDZ geometry

Is there any detailed documentation about RAIDZ geometry? I have been wandering
how zfs remembers which disk sectors are data and which ones are parity?

In his blog, Jeff wrote "Every block is its own RAID-Z stripe" does
that mean zfs writes exactly one block in every write action?

He also wrote "You have to traverse the filesystem metadata to determine
the RAID-Z geometry" where are these metadata stored?
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This message posted from opensolaris.org

> Is there any detailed documentation about RAIDZ geometry? I have  
> been wandering how zfs remembers which disk sectors are data and  
> which ones are parity?
Just in the source code:

  
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/fs/zfs/vdev_raidz.c
> In his blog, Jeff wrote "Every block is its own RAID-Z stripe"
does
> that mean zfs writes exactly one block in every write action?
Yes, and bear in mind that a block in ZFS is typically 128KB.
> He also wrote "You have to traverse the filesystem metadata to  
> determine the RAID-Z geometry" where are these metadata stored?

ZFS stores its data in a tree rooted at the uberblock. By filesystem  
metadata, Jeff is referring to this data storing this tree structure  
rather than user data.

Adam

--
Adam Leventhal, Fishworks                        http://blogs.sun.com/ahl