partitions

partitions

[Roberto Spadim]

hi guys, could we implement raid partitions?
for example:
mdadm --create /dev/md0 --level=1 --devices /dev/sda /dev/sdb
fdisk /dev/md0
create pratition 1,2,3,4

mkfs.ext4 /dev/md0p1
mkfs.ext4 /dev/md0p2
mkfs.ext4 /dev/md0p3
mkfs.ext4 /dev/md0p4

?? any idea? could we implement it?
there´s a TODO list for linux software raid?

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Roberto Spadim
Spadim Technology / SPAEmpresarial
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Re: partitions

[Roberto Spadim]

i read about lvm (not a lot), it work with grub and lilo right?

2011/1/28 Doug Dumitru <doug@easyco.com>:
> This functionality already exists with two different solutions.
>
> The "normal" solution is to use LVM on top of /dev/md0.  LVM is usually
> considered "better" than partitions because it is a more flexible approach.
>
> If you have to have partitions, you can do this with:
>
>     ... create partitions 1,2,3,4
>     kpartx -a /dev/md0
>     mkfs.ext4 /dev/mapper/md0p1
>     mkfs.ext4 /dev/mapper/md0p2
>     mkfs.ext4 /dev/mapper/md0p3
>     mkfs.ext4 /dev/mapper/md0p4
>
> This is not really a "linux-raid" issue, but just how to apply block device
> mapping tools.
>
> Doug Dumitru
> EasyCo LLC
>
> On Fri, Jan 28, 2011 at 1:24 PM, Roberto Spadim <roberto@spadim.com.br>
> wrote:
>>
>> hi guys, could we implement raid partitions?
>> for example:
>> mdadm --create /dev/md0 --level=1 --devices /dev/sda /dev/sdb
>> fdisk /dev/md0
>> create pratition 1,2,3,4
>>
>> mkfs.ext4 /dev/md0p1
>> mkfs.ext4 /dev/md0p2
>> mkfs.ext4 /dev/md0p3
>> mkfs.ext4 /dev/md0p4
>>
>> ?? any idea? could we implement it?
>> there愀 a TODO list for linux software raid?
>>
>> --
>> Roberto Spadim
>> Spadim Technology / SPAEmpresarial
>> --
>> 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
>
>
>
> --
> Doug Dumitru
> EasyCo LLC
>
>



-- 
Roberto Spadim
Spadim Technology / SPAEmpresarial
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Re: partitions

[Doug Dumitru]

On Fri, Jan 28, 2011 at 1:45 PM, Roberto Spadim <roberto@spadim.com.br> wrote:
>
> i read about lvm (not a lot), it work with grub and lilo right?

grub and lilo need a "plain" boot partition.  the raid setup is later
and your root partition can definitely be inside of an LVM volume.
This is the default install for many distros.

Doug Dumitru
EasyCo LLC

>
> 2011/1/28 Doug Dumitru <doug@easyco.com>:
> > This functionality already exists with two different solutions.
> >
> > The "normal" solution is to use LVM on top of /dev/md0.  LVM is usually
> > considered "better" than partitions because it is a more flexible approach.
> >
> > If you have to have partitions, you can do this with:
> >
> >     ... create partitions 1,2,3,4
> >     kpartx -a /dev/md0
> >     mkfs.ext4 /dev/mapper/md0p1
> >     mkfs.ext4 /dev/mapper/md0p2
> >     mkfs.ext4 /dev/mapper/md0p3
> >     mkfs.ext4 /dev/mapper/md0p4
> >
> > This is not really a "linux-raid" issue, but just how to apply block device
> > mapping tools.
> >
> > Doug Dumitru
> > EasyCo LLC
> >
> > On Fri, Jan 28, 2011 at 1:24 PM, Roberto Spadim <roberto@spadim.com.br>
> > wrote:
> >>
> >> hi guys, could we implement raid partitions?
> >> for example:
> >> mdadm --create /dev/md0 --level=1 --devices /dev/sda /dev/sdb
> >> fdisk /dev/md0
> >> create pratition 1,2,3,4
> >>
> >> mkfs.ext4 /dev/md0p1
> >> mkfs.ext4 /dev/md0p2
> >> mkfs.ext4 /dev/md0p3
> >> mkfs.ext4 /dev/md0p4
> >>
> >> ?? any idea? could we implement it?
> >> there愀 a TODO list for linux software raid?
> >>
> >> --
> >> Roberto Spadim
> >> Spadim Technology / SPAEmpresarial
> >> --
> >> 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
> >
> >
> >
> > --
> > Doug Dumitru
> > EasyCo LLC
> >
> >
>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial



--
Doug Dumitru
EasyCo LLC
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Re: partitions

[Roberto Spadim]

humm.... ok... no problems i was think about making software raid 100%
compatible with hardware raid (transparently) but it´s not just a plug
and play, no problems it´s easy :)

2011/1/28 Doug Dumitru <doug@easyco.com>:
> On Fri, Jan 28, 2011 at 1:45 PM, Roberto Spadim <roberto@spadim.com.br> wrote:
>>
>> i read about lvm (not a lot), it work with grub and lilo right?
>
> grub and lilo need a "plain" boot partition.  the raid setup is later
> and your root partition can definitely be inside of an LVM volume.
> This is the default install for many distros.
>
> Doug Dumitru
> EasyCo LLC
>
>>
>> 2011/1/28 Doug Dumitru <doug@easyco.com>:
>> > This functionality already exists with two different solutions.
>> >
>> > The "normal" solution is to use LVM on top of /dev/md0.  LVM is usually
>> > considered "better" than partitions because it is a more flexible approach.
>> >
>> > If you have to have partitions, you can do this with:
>> >
>> >     ... create partitions 1,2,3,4
>> >     kpartx -a /dev/md0
>> >     mkfs.ext4 /dev/mapper/md0p1
>> >     mkfs.ext4 /dev/mapper/md0p2
>> >     mkfs.ext4 /dev/mapper/md0p3
>> >     mkfs.ext4 /dev/mapper/md0p4
>> >
>> > This is not really a "linux-raid" issue, but just how to apply block device
>> > mapping tools.
>> >
>> > Doug Dumitru
>> > EasyCo LLC
>> >
>> > On Fri, Jan 28, 2011 at 1:24 PM, Roberto Spadim <roberto@spadim.com.br>
>> > wrote:
>> >>
>> >> hi guys, could we implement raid partitions?
>> >> for example:
>> >> mdadm --create /dev/md0 --level=1 --devices /dev/sda /dev/sdb
>> >> fdisk /dev/md0
>> >> create pratition 1,2,3,4
>> >>
>> >> mkfs.ext4 /dev/md0p1
>> >> mkfs.ext4 /dev/md0p2
>> >> mkfs.ext4 /dev/md0p3
>> >> mkfs.ext4 /dev/md0p4
>> >>
>> >> ?? any idea? could we implement it?
>> >> there愀 a TODO list for linux software raid?
>> >>
>> >> --
>> >> Roberto Spadim
>> >> Spadim Technology / SPAEmpresarial
>> >> --
>> >> 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
>> >
>> >
>> >
>> > --
>> > Doug Dumitru
>> > EasyCo LLC
>> >
>> >
>>
>>
>>
>> --
>> Roberto Spadim
>> Spadim Technology / SPAEmpresarial
>
>
>
> --
> Doug Dumitru
> EasyCo LLC
> --
> 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: partitions

[Hank Barta]

On Fri, Jan 28, 2011 at 4:39 PM, Doug Dumitru <doug@easyco.com> wrote:
>
> grub and lilo need a "plain" boot partition.  the raid setup is later
...

One exception: Grub (and perhaps LILO) can boot from a RAID1 partition
because the individual partition looks like a plain file system. It
requires v 0.9 metadata which stores the superblock at the end of the
partition. (Don't ask me how I know! ;) )

I have used LVM to partition a RAID5. I have no idea if it adds
significant overhead vs. partitioning the RAID itself if that were
possible. It was arcane enough for me to not care to do it again. It
appears to have some powerful capabilities that were not needed by me.

best,
hank

-- 
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Re: partitions

[Phillip Susi]

It already is.

On 01/28/2011 04:24 PM, Roberto Spadim wrote:
> hi guys, could we implement raid partitions?
> for example:
> mdadm --create /dev/md0 --level=1 --devices /dev/sda /dev/sdb
> fdisk /dev/md0
> create pratition 1,2,3,4
>
> mkfs.ext4 /dev/md0p1
> mkfs.ext4 /dev/md0p2
> mkfs.ext4 /dev/md0p3
> mkfs.ext4 /dev/md0p4
>
> ?? any idea? could we implement it?
> there´s a TODO list for linux software raid?
>

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Re: partitions

[Phillip Susi]

On 01/28/2011 08:22 PM, Hank Barta wrote:
> One exception: Grub (and perhaps LILO) can boot from a RAID1 partition
> because the individual partition looks like a plain file system. It
> requires v 0.9 metadata which stores the superblock at the end of the
> partition. (Don't ask me how I know! ;) )

Grub2 can boot from raid1, raid0, raid5, it doesn't care ( without a 
plain /boot partition ).

> I have used LVM to partition a RAID5. I have no idea if it adds
> significant overhead vs. partitioning the RAID itself if that were
> possible. It was arcane enough for me to not care to do it again. It
> appears to have some powerful capabilities that were not needed by me.

With LVM you can do online resize and moves, and don't run into issues 
trying to expand a partition and having to take forever to move an 
adjacent one over to make room, or other issues with the 4 primary 
partition limit.  I find these to be pretty handy.

Re: partitions

[Roberto Spadim]

nice i don't know if LVM make a more overhead but it's a very feature
=) thanks again guys!

2011/1/29 Phillip Susi <psusi@cfl.rr.com>:
> On 01/28/2011 08:22 PM, Hank Barta wrote:
>>
>> One exception: Grub (and perhaps LILO) can boot from a RAID1 partition
>> because the individual partition looks like a plain file system. It
>> requires v 0.9 metadata which stores the superblock at the end of the
>> partition. (Don't ask me how I know! ;) )
>
> Grub2 can boot from raid1, raid0, raid5, it doesn't care ( without a plain
> /boot partition ).
>
>> I have used LVM to partition a RAID5. I have no idea if it adds
>> significant overhead vs. partitioning the RAID itself if that were
>> possible. It was arcane enough for me to not care to do it again. It
>> appears to have some powerful capabilities that were not needed by me.
>
> With LVM you can do online resize and moves, and don't run into issues
> trying to expand a partition and having to take forever to move an adjacent
> one over to make room, or other issues with the 4 primary partition limit.
>  I find these to be pretty handy.
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
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>



-- 
Roberto Spadim
Spadim Technology / SPAEmpresarial
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