filesystem on mdadm raid from unpartioned block devices

filesystem on mdadm raid from unpartioned block devices

[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 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

Re: filesystem on mdadm raid from unpartioned block devices

[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 <garboge@shaw.ca>:
> 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
>
> --
> 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  http://vger.kernel.org/majordomo-info.html
>



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

[Roberto Spadim]

options for raid in mkfs.ext4:


                   stride=stride-size
                          Configure  the  filesystem  for  a  RAID  array with
                          stride-size filesystem blocks. This is the number 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  placement  of
                          filesystem metadata like bitmaps at mke2fs  time  to
                          avoid  placing them on a single disk, which can hurt
                          performance.  It may also be used by the block allo-
                          cator.



                   stripe-width=stripe-width
                          Configure  the  filesystem  for  a  RAID  array with
                          stripe-width filesystem blocks per stripe.  This  is
                          typically  stride-size * N, where N is the number of
                          data-bearing disks in the  RAID  (e.g.  for  RAID  5
                          there is one parity disk, so N will be the number 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´t know if it work


2011/1/12 Roberto Spadim <roberto@spadim.com.br>:
> i think that mkfs.ext4 is 4096 default block size
> -b 4096 is the option for device block size
>
>
> 2011/1/12 GarBoge <garboge@shaw.ca>:
>> 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
>>
>> --
>> 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  http://vger.kernel.org/majordomo-info.html
>>
>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial
>



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

[NeilBrown]

On Wed, 12 Jan 2011 15:31:37 -0700 GarBoge <garboge@shaw.ca> 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

Re: filesystem on mdadm raid from unpartioned block devices

[GarBoge]

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 <garboge@shaw.ca> 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
>