Erast Benson wrote:
> On Sun, 2008-03-30 at 21:33 -0700, Omen Wild wrote:
>   
>> Quoting Tim Spriggs <[EMAIL PROTECTED]> on Fri, Mar 28 12:08:
>>     
>>> I would suggest that you keep your entire root filesystem on the 
>>> mirror. apt-clone relies on this assumption in order to rollback 
>>> packaging decisions and does not snapshot/clone other filesystems.
>>>       
>> This raises a couple more questions about how pools work (I may be
>> wondering into ZFS only territory here).  Say I create a 100GB 3-way
>> mirror, and that becomes syspool.  The other 900GB disk partitions would
>> go into a raidz.  Would that be a new pool with a name of my choice?
Yes.
>>   Is
>> there an easy upgrade path when Open Solaris supports raidz boot besides
>> wipe and re-install?
Not exactly...
>>   From what I have read I could drop one disk out of
>> the raidz, re-add the entire disk into the raidz, and repeat for the
>> other 2 disks?  Would that work?
>>     
ATM you can not remove drives from a pool. However, you can use zfs 
send/zfs receive to exactly clone the syspool contents into a new pool. 
You would not be able to do this with the system live and would also 
take a few carefully chosen steps to accomplish. I imagine that someone 
will write up a migration guide when this becomes available.
>> Also, would I need to make the 3x100GB partitions be a straight mirror,
>> or could I make it a pool and tell ZFS to keep at least 2 copies of the
>> data, that way it would survive 1 disk failing, but is still a mirror
>> (of sorts).  Can GRUB boot from that kind of "mirror"?  Is it fully
>> robust against a single disk failure?  From the zfs blogs it seems as
>> if both copies could end up on the same disk...

You can make a 2 or 3-way mirror, or you can have a single device (not 
recommended but possible). It is also possible to have a single device 
for the pool and then add devices to form a mirror later on. For 
example, you could easily install Nexenta onto a single 100GB partition 
on the first drive, reboot, use Nexenta as you like and then at some 
point add another 100GB partition to create a 2-way mirror. You can also 
add a third 100GB partition as a hot spare so if one drive fails the 
third partition will take over and you will keep your syspool mirror 
redundancy. This might be desirable in a number of situations since 
having a 3-way mirror might incur slightly more expense in writes than a 
2-way mirror would.

There are all kinds of wonderful possibilities but you can only grow 
your pool, you can not reduce it.

-Tim
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