Also, when a pool is created, there is only metadata which uses
fletcher4[*].
So it is not a crime if you set the checksum after the pool is created
and before
data is written :-)
* note: the uberblock uses SHA-256
-- richard
On Oct 1, 2009, at 12:34 PM, Cindy Swearingen wrote:
You are correct. The zpool create -O option isn't available in a
Solaris 10 release but will be soon. This will allow you to set the
file system
checksum property when the pool is created:
# zpool create -O checksum=sha256 pool c1t1d0
# zfs get checksum pool
NAME PROPERTY VALUE SOURCE
pool checksum sha256 local
Otherwise, you would have to set it like this:
# zpool create pool c1t1d0
# zfs set checksum=sha256 pool
# zfs get checksum pool
NAME PROPERTY VALUE SOURCE
pool checksum sha256 local
I'm not sure I understand the second part of your comments but will
add:
If *you* rewrite your data then the new data will contain the new
checksum. I believe an upcoming project will provide the ability to
revise file system properties on the fly.
On 10/01/09 12:21, Ray Clark wrote:
U4 zpool does not appear to support the -o option... Reading a
current zpool manpage online lists the valid properties for the
current zpool -o, and checksum is not one of them. Are you
mistaken or am I missing something?
Another thought is that *perhaps* all of the blocks that comprise
an empty zpool are re-written sooner or later, and once the
checksum is changed with "zfs set checksum=sha256 zfs01" (The pool
name) they will be re-written with the new checksum very soon
anyway. Is this true? This would require an understanding of the
on-disk structure and when what is rewritten.
--Ray
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