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Old 10-12-2011, 03:48 PM
Les Mikesell
 
Default raid on large disks?

What's the right way to set up >2TB partitions for raid1 autoassembly?
I don't need to boot from this but I'd like it to come up and mount
automatically at boot.

--
Les Mikesell
lesmikesell@gmail.com
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Old 10-12-2011, 04:09 PM
John R Pierce
 
Default raid on large disks?

On 10/12/11 8:48 AM, Les Mikesell wrote:
> What's the right way to set up>2TB partitions for raid1 autoassembly?
> I don't need to boot from this but I'd like it to come up and mount
> automatically at boot.

disks 2TB and up have to be formatted as GPT rather than MBR, so old MBR
tools like fdisk are useless. use parted

I would build a LVM vg with the multi-terabyte volumes, using lvm
mirroring, and then create an XFS lv on the vg .... xfs seems 100%
stable and high performance on centos6


--
john r pierce N 37, W 122
santa cruz ca mid-left coast

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Old 10-12-2011, 04:14 PM
Les Mikesell
 
Default raid on large disks?

On Wed, Oct 12, 2011 at 11:09 AM, John R Pierce <pierce@hogranch.com> wrote:

>> What's the right way to set up>2TB partitions for raid1 autoassembly?
>> * I don't need to boot from this but I'd like it to come up and mount
>> automatically at boot.
>
> disks 2TB and up have to be formatted as GPT rather than MBR, so old MBR
> tools like fdisk are useless. *use parted
>
> I would build a LVM vg with the multi-terabyte volumes, using lvm
> mirroring, and then create an XFS lv on the vg .... * * xfs seems 100%
> stable and high performance on centos6

What I'm looking for is the way to make md raid autodetect and
assemble on boot. With fdisk, you would set the partition type to FD
for that, but I don't see an equivalent in parted.

--
Les Mikesell
lesmikesell@gmail.com
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Old 10-12-2011, 04:20 PM
David Miller
 
Default raid on large disks?

On Wed, Oct 12, 2011 at 12:14 PM, Les Mikesell <lesmikesell@gmail.com>wrote:

> On Wed, Oct 12, 2011 at 11:09 AM, John R Pierce <pierce@hogranch.com>
> wrote:
>
> >> What's the right way to set up>2TB partitions for raid1 autoassembly?
> >> I don't need to boot from this but I'd like it to come up and mount
> >> automatically at boot.
> >
> > disks 2TB and up have to be formatted as GPT rather than MBR, so old MBR
> > tools like fdisk are useless. use parted
> >
> > I would build a LVM vg with the multi-terabyte volumes, using lvm
> > mirroring, and then create an XFS lv on the vg .... xfs seems 100%
> > stable and high performance on centos6
>
> What I'm looking for is the way to make md raid autodetect and
> assemble on boot. With fdisk, you would set the partition type to FD
> for that, but I don't see an equivalent in parted.
>

With GPT that's set using flags. This is done in parted with the command
"set <partition number> raid on"
--
David
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Old 10-12-2011, 04:22 PM
David Miller
 
Default raid on large disks?

On Wed, Oct 12, 2011 at 12:20 PM, David Miller <david3d@gmail.com> wrote:

> On Wed, Oct 12, 2011 at 12:14 PM, Les Mikesell <lesmikesell@gmail.com>wrote:
>
>> On Wed, Oct 12, 2011 at 11:09 AM, John R Pierce <pierce@hogranch.com>
>> wrote:
>>
>> >> What's the right way to set up>2TB partitions for raid1 autoassembly?
>> >> I don't need to boot from this but I'd like it to come up and mount
>> >> automatically at boot.
>> >
>> > disks 2TB and up have to be formatted as GPT rather than MBR, so old MBR
>> > tools like fdisk are useless. use parted
>> >
>> > I would build a LVM vg with the multi-terabyte volumes, using lvm
>> > mirroring, and then create an XFS lv on the vg .... xfs seems 100%
>> > stable and high performance on centos6
>>
>> What I'm looking for is the way to make md raid autodetect and
>> assemble on boot. With fdisk, you would set the partition type to FD
>> for that, but I don't see an equivalent in parted.
>>
>
> With GPT that's set using flags. This is done in parted with the command
> "set <partition number> raid on"
>

I just thought of one other thing. You'll want to read up on bios boot if
these large drives are being used for the grub boot loader.
--
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Old 10-12-2011, 04:24 PM
John R Pierce
 
Default raid on large disks?

On 10/12/11 9:14 AM, Les Mikesell wrote:
> What I'm looking for is the way to make md raid autodetect and
> assemble on boot. With fdisk, you would set the partition type to FD
> for that, but I don't see an equivalent in parted.

set 1 raid on

but I was suggesting forgoing mdraid entirely, and using lvm mirroring
(lvcreate -m 2 ... vgname)

--
john r pierce N 37, W 122
santa cruz ca mid-left coast

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Old 10-12-2011, 04:28 PM
Les Mikesell
 
Default raid on large disks?

On Wed, Oct 12, 2011 at 11:22 AM, David Miller <david3d@gmail.com> wrote:
>>>
>> With GPT that's set using flags. *This is done in parted with the command
>> "set <partition number> raid on"
>>
>
> I just thought of one other thing. *You'll want to read up on bios boot if
> these large drives are being used for the grub boot loader.
>

Not booting from them, but is there a problem with kernel autoassembly
on large partitions? I see this in dmsg:

md: Autodetecting RAID arrays.
md: invalid raid superblock magic on sde1
md: sde1 has invalid sb, not importing!

But
mdadm --assemble /dev/md5 /dev/sde1
works fine after booting. (The array was created with a missing
member which hasn't been added yet).

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Les Mikesell
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Old 10-12-2011, 04:36 PM
Les Mikesell
 
Default raid on large disks?

On Wed, Oct 12, 2011 at 11:24 AM, John R Pierce <pierce@hogranch.com> wrote:
> On 10/12/11 9:14 AM, Les Mikesell wrote:
>> What I'm looking for is the way to make md raid autodetect and
>> assemble on boot. *With fdisk, you would set the partition type to FD
>> for that, but I don't see an equivalent in parted.
>
> set 1 raid on
>
> but I was suggesting forgoing mdraid entirely, and using lvm mirroring
> (lvcreate -m 2 ... vgname)

LVM seems unnecessarily complicated unless mdraid is broken on large
devices. And I already have data on the md partition (moving stuff
from a pair of 1.5TB drives to 3TB). If md isn't going to work, can I
put LVM on a single drive, add the data, then add the mirror (reusing
the one that now has the md partition and currently holding the data)?
The old disks are still around but not in the machine now.

--
Les Mikesell
lesmikesell@gmail.com
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Old 10-12-2011, 04:37 PM
"David C. Miller"
 
Default raid on large disks?

----- Original Message -----
> From: "Les Mikesell" <lesmikesell@gmail.com>
> To: "CentOS mailing list" <centos@centos.org>
> Sent: Wednesday, October 12, 2011 9:28:48 AM
> Subject: Re: [CentOS] raid on large disks?
>
> On Wed, Oct 12, 2011 at 11:22 AM, David Miller <david3d@gmail.com>
> wrote:
> >>>
> >> With GPT that's set using flags. *This is done in parted with the
> >> command
> >> "set <partition number> raid on"
> >>
> >
> > I just thought of one other thing. *You'll want to read up on bios
> > boot if
> > these large drives are being used for the grub boot loader.
> >
>
> Not booting from them, but is there a problem with kernel
> autoassembly
> on large partitions? I see this in dmsg:
>
> md: Autodetecting RAID arrays.
> md: invalid raid superblock magic on sde1
> md: sde1 has invalid sb, not importing!
>
> But
> mdadm --assemble /dev/md5 /dev/sde1
> works fine after booting. (The array was created with a missing
> member which hasn't been added yet).
>

When using mdadm you don't even have to partition a drive if you are using the whole thing. Just make sure the block device is set to GPT in parted if it is not already. After creating the RAID1 get the uuid of the raid by doing mdadm -D /dev/dm5. Then use the following format in the /etc/mdadm.conf to have it auto assemble at boot.

ARRAY /dev/md5 devices=/dev/sd[e-f] uuid=$UUID_FROM_MDADM

David C Miller.
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Old 10-12-2011, 04:55 PM
John R Pierce
 
Default raid on large disks?

On 10/12/11 9:36 AM, Les Mikesell wrote:
> LVM seems unnecessarily complicated unless mdraid is broken on large
> devices. And I already have data on the md partition (moving stuff
> from a pair of 1.5TB drives to 3TB). If md isn't going to work, can I
> put LVM on a single drive, add the data, then add the mirror (reusing
> the one that now has the md partition and currently holding the data)?
> The old disks are still around but not in the machine now.

I believe (from memory) you'd add the 2nd drive to the volume group, then

vgextend vgname /dev/(newdisk)
lvconvert -m 1 logicalvolumename

one nice thing about lvm mirroring is you can do it with a mix of drive
sizes without having to worry about geometry or layout, it will simply
ensure that each block exists on two devices....


--
john r pierce N 37, W 122
santa cruz ca mid-left coast

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