filesystem on mdadm raid from unpartioned block devices

A quick question that I haven't been able to find and answer for.

I have been using whole block devices (whole unpartitioned hard drives)
in various raid 1 and 5 setups using mdadm 3.1.4 with pretty mundane
options (default options such as striping and but using metadata 1.2).
Typically I use mkfs.ext4 with no options (default) to install the
filesystem.

Is there an issue with alignment on the newer 4096-byte drives. If so
what would be the proper approach?

I thank you for your time.

Ashley

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Re: filesystem on mdadm raid from unpartioned block devices

i think that mkfs.ext4 is 4096 default block size
-b 4096 is the option for device block size


2011/1/12 GarBoge :
> A quick question that I haven't been able to find and answer for.
>
> I have been using whole block devices (whole unpartitioned hard drive=
s)
> in various raid 1 and 5 setups using mdadm 3.1.4 with pretty mundane
> options (default options such as striping and but using metadata 1.2)=

> Typically I use mkfs.ext4 with no options (default) to install the
> filesystem.
>
> Is there an issue with alignment on the newer 4096-byte drives. If so
> what would be the proper approach?
>
> I thank you for your time.
>
> Ashley
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid"=
in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html
>



--=20
Roberto Spadim
Spadim Technology / SPAEmpresarial
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Re: filesystem on mdadm raid from unpartioned block devices

options for raid in mkfs.ext4:


stride=3Dstride-size
Configure the filesystem for a RAID arr=
ay with
stride-size filesystem blocks. This is the nu=
mber of
blocks read or written to disk before moving=
to the
next disk, which is sometimes referred to =
as the
chunk size. This mostly affects placem=
ent of
filesystem metadata like bitmaps at mke2fs t=
ime to
avoid placing them on a single disk, which c=
an hurt
performance. It may also be used by the bloc=
k allo-
cator.



stripe-width=3Dstripe-width
Configure the filesystem for a RAID arr=
ay with
stripe-width filesystem blocks per stripe. T=
his is
typically stride-size * N, where N is the nu=
mber of
data-bearing disks in the RAID (e.g. for =
RAID 5
there is one parity disk, so N will be the nu=
mber of
disks in the array minus 1). This allows the=
block
allocator to prevent read-modify-write of the=
parity
in a RAID stripe if possible when the data is=
writ-
ten.


i don=B4t know if it work


2011/1/12 Roberto Spadim :
> i think that mkfs.ext4 is 4096 default block size
> -b 4096 is the option for device block size
>
>
> 2011/1/12 GarBoge :
>> A quick question that I haven't been able to find and answer for.
>>
>> I have been using whole block devices (whole unpartitioned hard driv=
es)
>> in various raid 1 and 5 setups using mdadm 3.1.4 with pretty mundane
>> options (default options such as striping and but using metadata 1.2=
).
>> Typically I use mkfs.ext4 with no options (default) to install the
>> filesystem.
>>
>> Is there an issue with alignment on the newer 4096-byte drives. If s=
o
>> what would be the proper approach?
>>
>> I thank you for your time.
>>
>> Ashley
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-raid=
" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html
>>
>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial
>



--=20
Roberto Spadim
Spadim Technology / SPAEmpresarial
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Re: filesystem on mdadm raid from unpartioned block devices

On Wed, 12 Jan 2011 15:31:37 -0700 GarBoge wrote:

> A quick question that I haven't been able to find and answer for.
>
> I have been using whole block devices (whole unpartitioned hard drives)
> in various raid 1 and 5 setups using mdadm 3.1.4 with pretty mundane
> options (default options such as striping and but using metadata 1.2).
> Typically I use mkfs.ext4 with no options (default) to install the
> filesystem.
>
> Is there an issue with alignment on the newer 4096-byte drives. If so
> what would be the proper approach?

No, no issue.

NeilBrown


>
> I thank you for your time.
>
> Ashley

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Re: filesystem on mdadm raid from unpartioned block devices

Thanks for the quick reply. I thank you for the great mdadm software.

Ashley


On Thu, 2011-01-13 at 13:00 +1100, NeilBrown wrote:
> On Wed, 12 Jan 2011 15:31:37 -0700 GarBoge wrote:
>
> > A quick question that I haven't been able to find and answer for.
> >
> > I have been using whole block devices (whole unpartitioned hard drives)
> > in various raid 1 and 5 setups using mdadm 3.1.4 with pretty mundane
> > options (default options such as striping and but using metadata 1.2).
> > Typically I use mkfs.ext4 with no options (default) to install the
> > filesystem.
> >
> > Is there an issue with alignment on the newer 4096-byte drives. If so
> > what would be the proper approach?
>
> No, no issue.
>
> NeilBrown
>
>
> >
> > I thank you for your time.
> >
> > Ashley
>


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