Roch - PAE wrote:
> [EMAIL PROTECTED] writes:
>  > Jim Mauro wrote:
>  > >
>  > > Hey Max - Check out the on-disk specification document at
>  > > http://opensolaris.org/os/community/zfs/docs/.
>  > >
>  > > Page 32 illustration shows the rootbp pointing to a dnode_phys_t
>  > > object (the first member of a objset_phys_t data structure).
>  > >
>  > > The source code indicates ub_rootbp is a blkptr_t, which contains
>  > > a 3 member array of dva_t 's called blk_dva (blk_dva[3]).
>  > > Each dva_t is a 2 member array of 64-bit unsigned ints (dva_word[2]).
>  > >
>  > > So it looks like each blk_dva contains 3 128-bit DVA's....
>  > >
>  > > You probably figured all this out already....did you try using
>  > > a objset_phys_t to format the data?
>  > >
>  > > Thanks,
>  > > /jim
>  > Ok.  I think I know what's wrong.  I think the information (most likely, 
>  > a objset_phys_t) is compressed
>  > with lzjb compression.  Is there a way to turn this entirely off (not 
>  > just for file data, but for all meta data
>  > as well when a pool is created?  Or do I need to figure out how to hack 
>  > in the lzjb_decompress() function in
>  > my modified mdb?  (Also, I figured out that zdb is already doing the 
>  > left shift by 9 before dumping DVA values,
>  > for anyone following this...).
>  > 
>
> Max, this might help (zfs_mdcomp_disable) :
> http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide#METACOMP
>   
Hi Roch,
That would help, except it does not seem to work.  I set 
zfs_mdcomp_disable to 1 with mdb,
deleted the pool, recreated the pool, and zdb -uuuu still shows the 
rootbp in the uberblock_t
to have the lzjb flag turned on.  So I then added the variable to 
/etc/system, destroyed the pool,
rebooted, recreated the pool, and still the same result.  Also, my mdb 
shows the same thing
for the uberblock_t rootbp blkptr data.   I am running Nevada build 55b.

I shall update the build I am running soon, but in the meantime I'll 
probably write a modified cmd_print() function for my
(modified)  mdb to handle (at least) lzjb compressed metadata.  Also, I 
think the ZFS Evil Tuning Guide should be
modified.  It says this can be tuned for Solaris 10 11/06 and snv_52.  I 
guess that means only those
two releases.  snv_55b has the variable, but it doesn't have an effect 
(at least on the uberblock_t
rootbp meta-data).

thanks for your help.

max

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