raid1 and raid 10 always writes all data to all disks?

raid1 and raid 10 always writes all data to all disks?

[Keld Jørn Simonsen]

 I found a sentence in the HOWTO:

"raid1 and raid 10 always writes all data to all disks"

I think this is wrong for raid10.

eg

a raid10,f2 of 4 disks only writes to two of the disks -
not all 4 disks. Is that true?

best regards
keld

Re: raid1 and raid 10 always writes all data to all disks?

[Bill Davidsen]

Keld Jørn Simonsen wrote:
>  I found a sentence in the HOWTO:
>
> "raid1 and raid 10 always writes all data to all disks"
>
> I think this is wrong for raid10.
>
> eg
>
> a raid10,f2 of 4 disks only writes to two of the disks -
> not all 4 disks. Is that true?
>   

I suspect that really should have read "all mirror copies," in the 
raid10 case.

-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark 



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Re: raid1 and raid 10 always writes all data to all disks?

[Keld Jørn Simonsen]

On Sun, Feb 03, 2008 at 10:56:01AM -0500, Bill Davidsen wrote:
> Keld Jørn Simonsen wrote:
> > I found a sentence in the HOWTO:
> >
> >"raid1 and raid 10 always writes all data to all disks"
> >
> >I think this is wrong for raid10.
> >
> >eg
> >
> >a raid10,f2 of 4 disks only writes to two of the disks -
> >not all 4 disks. Is that true?
> >  
> 
> I suspect that really should have read "all mirror copies," in the 
> raid10 case.

OK, I changed the text to:

raid1 always writes all data to all disks.

raid10 always writes all data to the number of copies that the raid holds.
For example on a raid10,f2 or raid10,o2 of 6 disks, the data will only
be written 2 times.

Best regards
Keld
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Re: raid1 and raid 10 always writes all data to all disks?

[Bill Davidsen]

Keld Jørn Simonsen wrote:
> On Sun, Feb 03, 2008 at 10:56:01AM -0500, Bill Davidsen wrote:
>   
>> Keld Jørn Simonsen wrote:
>>     
>>> I found a sentence in the HOWTO:
>>>
>>> "raid1 and raid 10 always writes all data to all disks"
>>>
>>> I think this is wrong for raid10.
>>>
>>> eg
>>>
>>> a raid10,f2 of 4 disks only writes to two of the disks -
>>> not all 4 disks. Is that true?
>>>  
>>>       
>> I suspect that really should have read "all mirror copies," in the 
>> raid10 case.
>>     
>
> OK, I changed the text to:
>
> raid1 always writes all data to all disks.
>   

Just to be really pedantic, you might say "devices" instead of disks, 
since many or most arrays are on partitions. Otherwise I like this, it's 
much clearer.
> raid10 always writes all data to the number of copies that the raid holds.
> For example on a raid10,f2 or raid10,o2 of 6 disks, the data will only
> be written 2 times.
>
> Best regards
> Keld
>
>   


-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark 



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