modified mdb for examining zfs on disk
This contains changes for usr/src/cmd/mdb/common/mdb/mdb_rawfile.c, usr/src/cmd/mdb/common/modules/zfs/zfs.c, and source for zuncompress.c and rawzfs.c Also included are binaries:
mdb - with changes to look at ZFS on disk zfs.so - slight change to be used with mdb rawzfs.so - new mdb dmod for the ::walk uberblock command zuncompress - uncompress data
To see these in use, see the Bruning Questions blog post at http://www.joyent.com/blog/zfs-forensics-recovering-files-from-a-destroyed-zpool.
To build, start with http://wiki.smartos.org/display/DOC/Building+SmartOS+on+SmartOS and follow all of the instructions there. Then copy mdb_rawfile.c from here to smartos-live/projects/illumos/usr/src/cmd/mdb/common/mdb/mdb_rawfile.c, zfs.c from here to smartos-live/projects/illumos/usr/src/cmd/mdb/common/modules/zfs.c, and rawzfs.c to smartos-live/projects/illumos/usr/src/cmd/mdb/common/modules/rawzfs.c. You may need to edit the mdb Makefile to get rawzfs.so to build, but it should be pretty straight forward. To build zuncompress: gcc -m64 -I ./smartos-live/projects/illumos/usr/src/uts/common/fs/zfs -lzfs -lzpool -o zuncompress zuncompress.c
This is very much a work in progress. In its final form, I expect someone will make a ZFS on disk target for mdb, and the hacks in mdb_rawfile.c can go away. There are lots of dcmds and walkers that could be written that would be interesting. For instance, object_id_#::dnodefind [-d dataset] [-p zpool]. But the best would be: disk_address::zprint [-c compression_algorithm] datatype Then there would be no need to use zuncompress, and you could do everything in 1 mdb session.