On Wed, Jul 19, 2006 at 03:10:00AM +0200, [EMAIL PROTECTED] wrote:
> So how many of the 128 bits of the blockpointer are used for things
> other than to point where the block is?
128 *bits*? What filesystem have you been using? :) We've got
luxury-class block pointers that are 128 *bytes*. We get away with it
because we also have big data blocks to go with them. In your typical
mixed-data storage pool, about 1-2% total (including all the block
pointers) is ZFS metadata, everything else is real user data. The
breakdown of a block pointer is roughly:
3 x 128 bits - DVAs (up to 3-way ditto blocks)
1 x 64 bits - misc. properties
1 x 64 bits - block birth
1 x 64 bits - fill count
1 x 256 bits - checksum
3 x 64 bits - future growth (some to be used by encryption)
See this for details:
http://cvs.opensolaris.org/source/xref/on/usr/src/uts/common/fs/zfs/sys/spa.h
--Bill
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