On Mar 27, 2010, at 5:07 AM, John R Pierce <pierce@xxxxxxxxxxxx> wrote:
> Robert Spangler wrote:
>> On Thursday 25 March 2010 18:10, Robert Heller wrote:
>>
>>
>>> The prefered way to go would be RAID10 (RAID1 (mirror) + RAID0
>>> (stripe)).
>>> Form pairs as RAID1, then strip the pairs. With 8 disks, this
>>> would 4
>>> pairs, 1.5TB/pair = 1.5*4 = 6TB total.
>>>
>>
>> I am just starting to look into this RAID and I was wondering
>> wouldn't RAID01
>> be better then RAID10? In a 4 disc system having the first two using
>> stripping and then backing them up the second set with mirrors?
>>
>> My though is having D1 and D2 as the primary drives stripping and
>> then having
>> D3 backup D1 and D4 backup D2.
>>
>> And if enough room place a couple more drives in the system as hot
>> standby's.
>>
>> Or am I looking at this all wrong?
>>
>
>
> for all practical purposes its the same thing. if it was really
> stripe then mirror, a naive mirror handler would think it would have
> to
> remirror both drives when one half of one of the stripesets failed and
> was replaced. but in fact, the mirror handlres tend to be well
> aware
> of whats going on. mirror 0+1 aand stripe that with mirrored
> 2+3,
> and its really all the same the native raid10 in newer mdraid is
> cleaner because you don't end up with extra partial volume
> metadevices...
RAID0+1 is never a good configuration because a single drive failure
in a RAID0 stripe fails out the whole stripe, and with say an 4x2
RAID0+1, you are more likely to hit a disk failure with 4 drives in a
RAID0 then 2 in a RAID1.
That's why RAID1+0 came about.
-Ross
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