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Date: Wed, 30 Jan 2013 18:31:38 +0400
From: Artem Kuchin <matrix@itlegion.ru>
Organization: IT Legion
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To: Warren Block <wblock@wonkity.com>
Subject: Re: Software raid VS hardware raid
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30.01.2013 18:06, Warren Block:
> On Wed, 30 Jan 2013, Artem Kuchin wrote:
>
>>
>> 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.
>
> If only one GPT partition on a drive is mirrored with another GPT 
> partition on another drive, head contention never comes up.  There is 
> only one mirror.
>
> It does nearly eliminate the usefulness of GPT partitioning.
>
Um... and how can i do that if i have a simple mirror with two drives 
and want to mirror everything on them? As i understand i will have at least
bootable, swap and ufs parttions on those drives, that is 3 partitions 
at least.

Artem