mdadm striped parity RAID with Advanced Format drives

On 7/21/2011 3:11 AM, Pol Hallen wrote:
> Hello and sorry if I write you in private..

No worries. I'm taking this back on list as others have more experience
with this than me.

> about 2Tb wd and 4Kb size, is there a howto to check and correct the size of
> these disks?
>
> Can you tell me how?

> Model Number: WDC WD20EARS-00MVWB0

1. Can one create a RAID5 from bare (partition-less) AF drives and avoid
the read-modify-write problem?

2. Or is one required to assemble the array from properly aligned
partitions created on each drive?

Pol, *IF* the answer to #1 is yes, creating the array properly becomes
easier. Simply create the array with raw device names and no partition
numbers, for example, sd[a,b,c,d,e,f]. If you've already created
partitions on the drives, wipe everything off all drives, including the
partitions tables.

If the answer to #1 is 'no', and to #2 is 'yes', then you need to follow
the instructions posted by Erwan Leroux.

--
Stan
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Re: mdadm striped parity RAID with Advanced Format drives

On Thu, 21 Jul 2011, Stan Hoeppner wrote:

> 1. Can one create a RAID5 from bare (partition-less) AF drives and avoid
> the read-modify-write problem?

Yes, that's what I always do.

> 2. Or is one required to assemble the array from properly aligned
> partitions created on each drive?

No.

--
Mikael Abrahamsson email: swmike@swm.pp.se
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Re: mdadm striped parity RAID with Advanced Format drives

> Pol, *IF* the answer to #1 is yes, creating the array properly becomes
> easier. Simply create the array with raw device names and no partition
> numbers, for example, sd[a,b,c,d,e,f]. If you've already created
> partitions on the drives, wipe everything off all drives, including the
> partitions tables.
> If the answer to #1 is 'no', and to #2 is 'yes', then you need to follow
> the instructions posted by Erwan Leroux.

Thanks for your courtesy :-)

tonight I disasseble whole raid and check again disks, next I'll create a raid
and will do performance test, that I'll post to list.

Thanks again :-)

Pol
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Re: mdadm striped parity RAID with Advanced Format drives

On Thu, Jul 21, 2011 at 05:26:22AM -0500, Stan Hoeppner wrote:
>On 7/21/2011 3:11 AM, Pol Hallen wrote:
>> Hello and sorry if I write you in private..
>
>No worries. I'm taking this back on list as others have more experience
>with this than me.
>
>> about 2Tb wd and 4Kb size, is there a howto to check and correct the size of
>> these disks?
>>
>> Can you tell me how?
>
>> Model Number: WDC WD20EARS-00MVWB0
>
>1. Can one create a RAID5 from bare (partition-less) AF drives and avoid
>the read-modify-write problem?

until someone proves me wrong i believe 0 is divisible both by 512 and
4096.

L.

--
Luca Berra -- bluca@comedia.it
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