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Date: Wed, 30 Jan 2013 15:42:25 +0400
From: Artem Kuchin <matrix@itlegion.ru>
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To: Warren Block <wblock@wonkity.com>
Subject: Re: Software raid VS hardware raid
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30.01.2013 1:01, Warren Block:
> On Tue, 29 Jan 2013, Artem Kuchin wrote:
>
>>
>> 29.01.2013 18:57, Warren Block:
>>> On Tue, 29 Jan 2013, Artem Kuchin wrote:
>>>
>>> The Handbook chapter on gmirror talks about the problems with GPT 
>>> and GEOM metadata.  In short: right now, they conflict. It's 
>>> possible to mirror GPT partitions, but be aware that if you mirror 
>>> more than one partition on a drive, a rebuild after replacing a 
>>> drive could thrash the heads as mirrors are rebuilt simultaneously.
>>>
>>> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-mirror.html 
>>>
>>>
>>
>> So,
>> gmirror+GPT=conflict on last sector
>> GPT+gmirror = hardrive head kill
>>
>> nice...
>>
>> So, for no more than 2TB disks the best way to go is GMIRROR of the 
>> drive +PARTITION on top of it?
>
> GPT partitions should work, just limit it to one mirrored partition 
> per drive.

Please, clarify what you mean here.

>
>> Or maybe there is a way to instruct gmirror do rebuild only what i 
>> say (manual rebuild) ?
>
> 'gmirror configure -n' ?  Have not tried it.  The trick would be to do 
> that before multiple mirrors start rebuilding, which they will as soon 
> as geom_mirror.ko is loaded.
>

As i understand from the man page -n  setup the device not to auto 
rebuild  ever. So, this is probably the thing i want.  I need to setup a 
test system and play with it
a bit.


Artem