[nylug-talk] How to set up Raid 1 on Ubuntu, Or Linux in gerneral

[Henning Follmann]

On Jun 1, 2007, at 3:22 PM, alex at pilosoft.com wrote:

> On Fri, 1 Jun 2007, Henning Follmann wrote:
>
>>
>> On Jun 1, 2007, at 2:08 PM, sixtyfourbeets wrote:
>>
>>>
>>> Convention dictates that when constructing a true SAN one should buy
>>> drives from different manufacturers.  Doing so addresses the concern
>>> that a particular drive will not be the same as the next drive in  
>>> the
>>> SAN.  The reasoning behind that is if drives are from different
>>> manufactures chances are less likely that the drives will fail in a
>>> similar fashion in a reasonably short time span.
>>>
>>> Steve M
>>
>> Sorry there is no reasonable logic in what you just wrote.
>>
>> Do you seriously think that two hard drives because they are built  
>> on a
>> same day in the same place will fail also on the same day? I think  
>> it is
>> more likely two win twice in the lottery in the same week with the  
>> same
>> numbers.
> Unfortunately, even the worst trolls are occasionally right. Yes,  
> drives
> from same batch often fail concurrently. IE. the correlation between
> failure times on same batch is non-zero.
>
> There are some papers on that too.

I am not disputing that. OTH two drives from different manufacturers  
failing on the same day the chance is also non zero.
I usually have raid 5 or mirroring. So I care about the chance that  
in my set another drive fails before I could swap and rebuild.
I still do not think that drives from the same lot fail that close  
together.

Henning


-- 
Henning Follmann           | hfollmann at itcfollmann.com
it consultant              | www.itcfollmann.com