raid10 on centos 5

raid10 on centos 5

[Ruslan Sivak]

I am trying to set up raid 10 and so far with no luck.  I have 4 drives, 
and Anaconda will not let me do raid 10.  mdadm doesn't have the raid 10 
personality loaded.  When I create the array manually like so:

2 drives in /dev/md11 as raid1
2 drives in /dev/md12 as raid1
md11 and md12 in /dev/md10 as raid0

Everything looks fine from the shell, but anaconda only sees md11 and 
md12. 

The only choice I see is to set up LVM over md11 and md12.  Is this 
really raid10?

Russ

RE: raid10 on centos 5

[Patrick_Boyd]

No LVM over the two RAID 1's is more like RAID 1c which is just a
concatenation of RAID 1's. You don't get the striping that you get in
RAID 10.

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Ruslan Sivak
Sent: Friday, May 04, 2007 11:22 AM
To: linux-raid@vger.kernel.org
Subject: raid10 on centos 5

I am trying to set up raid 10 and so far with no luck.  I have 4 drives,

and Anaconda will not let me do raid 10.  mdadm doesn't have the raid 10

personality loaded.  When I create the array manually like so:

2 drives in /dev/md11 as raid1
2 drives in /dev/md12 as raid1
md11 and md12 in /dev/md10 as raid0

Everything looks fine from the shell, but anaconda only sees md11 and 
md12. 

The only choice I see is to set up LVM over md11 and md12.  Is this 
really raid10?

Russ


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Re: raid10 on centos 5

[Ruslan Sivak]

Patrick_Boyd@Dell.com wrote:
> No LVM over the two RAID 1's is more like RAID 1c which is just a
> concatenation of RAID 1's. You don't get the striping that you get in
> RAID 10.
>
>   
That's what I guessed.  Can anyone let me know if it's possible to set 
up a real md raid10?  Do I need to custom compile the kernel and do a 
kickstart install or something?

Russ

Re: raid10 on centos 5

[Justin Piszcz]

cat /proc/mdstat

is the raid10 personality installed?

On Fri, 4 May 2007, Ruslan Sivak wrote:

> Patrick_Boyd@Dell.com wrote:
>> No LVM over the two RAID 1's is more like RAID 1c which is just a
>> concatenation of RAID 1's. You don't get the striping that you get in
>> RAID 10.
>>
>> 
> That's what I guessed.  Can anyone let me know if it's possible to set up a 
> real md raid10?  Do I need to custom compile the kernel and do a kickstart 
> install or something?
>
> Russ
> -
> 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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>

Re: raid10 on centos 5

[Ruslan Sivak]

Justin Piszcz wrote:
> cat /proc/mdstat
>
> is the raid10 personality installed?
>
No, it's not.  How would I go about installing it?

Personalities: [raid0] [raid1] [raid6] [raid5] [raid4]

Russ

Re: raid10 on centos 5

[Justin Piszcz]

Compile into the kernel, boot new kernel then create your RAID 10 volume 
with mdadm :)


On Fri, 4 May 2007, Ruslan Sivak wrote:

> Justin Piszcz wrote:
>> cat /proc/mdstat
>> 
>> is the raid10 personality installed?
>> 
> No, it's not.  How would I go about installing it?
>
> Personalities: [raid0] [raid1] [raid6] [raid5] [raid4]
>
> Russ
> -
> 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
>

Re: raid10 on centos 5

[Ruslan Sivak]

Justin Piszcz wrote:
> Compile into the kernel, boot new kernel then create your RAID 10 
> volume with mdadm :)
>
>
So a custom kernel is needed?  Is there a way to do a kickstart install 
with the new kernel?  Or better yet, put it on the install cd?

Russ

Re: raid10 on centos 5

[Justin Piszcz]

Unsure for CentOS, I use Debian and always compile my own kernel.

Justin.

On Fri, 4 May 2007, Ruslan Sivak wrote:

> Justin Piszcz wrote:
>> Compile into the kernel, boot new kernel then create your RAID 10 volume 
>> with mdadm :)
>> 
>> 
> So a custom kernel is needed?  Is there a way to do a kickstart install with 
> the new kernel?  Or better yet, put it on the install cd?
>
> Russ
>
>

Re: raid10 on centos 5

[David Greaves]

Ruslan Sivak wrote:
> So a custom kernel is needed?  Is there a way to do a kickstart install
> with the new kernel?  Or better yet, put it on the install cd?

have you tried:
 modprobe raid10

?

David

Re: raid10 on centos 5

[Ruslan Sivak]

David Greaves wrote:
> Ruslan Sivak wrote:
>   
>> So a custom kernel is needed?  Is there a way to do a kickstart install
>> with the new kernel?  Or better yet, put it on the install cd?
>>     
>
> have you tried:
>  modprobe raid10
>
> ?
>
> David
>   
Yes, no such luck. 

Russ

RE: raid10 on centos 5

[Guy Watkins]

} -----Original Message-----
} From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
} owner@vger.kernel.org] On Behalf Of Ruslan Sivak
} Sent: Friday, May 04, 2007 12:22 PM
} To: linux-raid@vger.kernel.org
} Subject: raid10 on centos 5
} 
} I am trying to set up raid 10 and so far with no luck.  I have 4 drives,
} and Anaconda will not let me do raid 10.  mdadm doesn't have the raid 10
} personality loaded.  When I create the array manually like so:
} 
} 2 drives in /dev/md11 as raid1
} 2 drives in /dev/md12 as raid1
} md11 and md12 in /dev/md10 as raid0
} 
} Everything looks fine from the shell, but anaconda only sees md11 and
} md12.
} 
} The only choice I see is to set up LVM over md11 and md12.  Is this
} really raid10?
} 
} Russ

You are making a RAID1+RAID0 array.
Try making a real RAID10 array with 4 drives.  This way you would only have
1 array with 4 drives.

From the mdadm man page:
Currently, Linux supports LINEAR md devices,  RAID0  (striping),  RAID1
       (mirroring), RAID4, RAID5, RAID6, RAID10, MULTIPATH, and FAULTY.

Notice RAID10 is listed, use that.  Man mdadm for more info.

However, I would (and do) use RAID6.  With RAID6 any 2 disks can fail
without data loss.  With RAID1+RAID0, any one disk can fail, a second
failure has a 1 in 3 chance of vast data loss.

I hope this helps,
Guy

Re: raid10 on centos 5

[Ruslan Sivak]

Guy Watkins wrote:
> } -----Original Message-----
> } From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
> } owner@vger.kernel.org] On Behalf Of Ruslan Sivak
> } Sent: Friday, May 04, 2007 12:22 PM
> } To: linux-raid@vger.kernel.org
> } Subject: raid10 on centos 5
> } 
> } I am trying to set up raid 10 and so far with no luck.  I have 4 drives,
> } and Anaconda will not let me do raid 10.  mdadm doesn't have the raid 10
> } personality loaded.  When I create the array manually like so:
> } 
> } 2 drives in /dev/md11 as raid1
> } 2 drives in /dev/md12 as raid1
> } md11 and md12 in /dev/md10 as raid0
> } 
> } Everything looks fine from the shell, but anaconda only sees md11 and
> } md12.
> } 
> } The only choice I see is to set up LVM over md11 and md12.  Is this
> } really raid10?
> } 
> } Russ
>
> You are making a RAID1+RAID0 array.
> Try making a real RAID10 array with 4 drives.  This way you would only have
> 1 array with 4 drives.
>
> >From the mdadm man page:
> Currently, Linux supports LINEAR md devices,  RAID0  (striping),  RAID1
>        (mirroring), RAID4, RAID5, RAID6, RAID10, MULTIPATH, and FAULTY.
>
> Notice RAID10 is listed, use that.  Man mdadm for more info.
>
> However, I would (and do) use RAID6.  With RAID6 any 2 disks can fail
> without data loss.  With RAID1+RAID0, any one disk can fail, a second
> failure has a 1 in 3 chance of vast data loss.
>
> I hope this helps,
> Guy
>
> -
>   


Guy,

That's what I've been trying to do.  Unfortunatelly, my distro, CentOS 5 
(based on RHEL 5, I believe), does not have the RAID10 personality in 
the kernel.  I guess I would have to compile my own kernel and load the 
module through a driver disk.  Would that work?  Are there some 
instructions somewhere I can follow?

Russ

Re: raid10 on centos 5

[Eli Stair]

You shouldn't need to build a new kernel, just extract the SRPM for the initial 
install (CentOS 5, no updated kernels), use the config for the appropriate kernel 
(SMP, UP, i386/x86_64), enable the raid10 module and do a 'make modules'.  You may 
need to do a minor amount of tweaking in the installer image to include this, but 
nothing serious.  Alternately, just building a driver disk with the module and 
source it in the install.  Interesting that it's not enabled in the installer 
image, because it's present in a fully-booted system... space limitations?


/eli

Ruslan Sivak wrote:
> Guy Watkins wrote:
>  > } -----Original Message-----
>  > } From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
>  > } owner@vger.kernel.org] On Behalf Of Ruslan Sivak
>  > } Sent: Friday, May 04, 2007 12:22 PM
>  > } To: linux-raid@vger.kernel.org
>  > } Subject: raid10 on centos 5
>  > }
>  > } I am trying to set up raid 10 and so far with no luck.  I have 4 
> drives,
>  > } and Anaconda will not let me do raid 10.  mdadm doesn't have the 
> raid 10
>  > } personality loaded.  When I create the array manually like so:
>  > }
>  > } 2 drives in /dev/md11 as raid1
>  > } 2 drives in /dev/md12 as raid1
>  > } md11 and md12 in /dev/md10 as raid0
>  > }
>  > } Everything looks fine from the shell, but anaconda only sees md11 and
>  > } md12.
>  > }
>  > } The only choice I see is to set up LVM over md11 and md12.  Is this
>  > } really raid10?
>  > }
>  > } Russ
>  >
>  > You are making a RAID1+RAID0 array.
>  > Try making a real RAID10 array with 4 drives.  This way you would 
> only have
>  > 1 array with 4 drives.
>  >
>  > >From the mdadm man page:
>  > Currently, Linux supports LINEAR md devices,  RAID0  (striping),  RAID1
>  >        (mirroring), RAID4, RAID5, RAID6, RAID10, MULTIPATH, and FAULTY.
>  >
>  > Notice RAID10 is listed, use that.  Man mdadm for more info.
>  >
>  > However, I would (and do) use RAID6.  With RAID6 any 2 disks can fail
>  > without data loss.  With RAID1+RAID0, any one disk can fail, a second
>  > failure has a 1 in 3 chance of vast data loss.
>  >
>  > I hope this helps,
>  > Guy
>  >
>  > -
>  >  
> 
> 
> Guy,
> 
> That's what I've been trying to do.  Unfortunatelly, my distro, CentOS 5
> (based on RHEL 5, I believe), does not have the RAID10 personality in
> the kernel.  I guess I would have to compile my own kernel and load the
> module through a driver disk.  Would that work?  Are there some
> instructions somewhere I can follow?
> 
> Russ
> 
> 
> -
> 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
> 

Re: raid10 on centos 5

[Ruslan Sivak]

Eli Stair wrote:
>
> You shouldn't need to build a new kernel, just extract the SRPM for 
> the initial install (CentOS 5, no updated kernels), use the config for 
> the appropriate kernel (SMP, UP, i386/x86_64), enable the raid10 
> module and do a 'make modules'.  You may need to do a minor amount of 
> tweaking in the installer image to include this, but nothing serious.  
> Alternately, just building a driver disk with the module and source it 
> in the install.  Interesting that it's not enabled in the installer 
> image, because it's present in a fully-booted system... space 
> limitations?
>
>
> /eli
>
It is not present in a fully booted system for me either.  Are you 
running centos 5? 

How would I make a driver disk?  I'm not very familiar with this. 

Russ

RE: raid10 on centos 5

[Guy Watkins]

} -----Original Message-----
} From: Ruslan Sivak [mailto:rsivak@istandfor.com]
} Sent: Friday, May 04, 2007 7:22 PM
} To: Guy Watkins
} Cc: linux-raid@vger.kernel.org
} Subject: Re: raid10 on centos 5
} 
} Guy Watkins wrote:
} > } -----Original Message-----
} > } From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
} > } owner@vger.kernel.org] On Behalf Of Ruslan Sivak
} > } Sent: Friday, May 04, 2007 12:22 PM
} > } To: linux-raid@vger.kernel.org
} > } Subject: raid10 on centos 5
} > }
} > } I am trying to set up raid 10 and so far with no luck.  I have 4
} drives,
} > } and Anaconda will not let me do raid 10.  mdadm doesn't have the raid
} 10
} > } personality loaded.  When I create the array manually like so:
} > }
} > } 2 drives in /dev/md11 as raid1
} > } 2 drives in /dev/md12 as raid1
} > } md11 and md12 in /dev/md10 as raid0
} > }
} > } Everything looks fine from the shell, but anaconda only sees md11 and
} > } md12.
} > }
} > } The only choice I see is to set up LVM over md11 and md12.  Is this
} > } really raid10?
} > }
} > } Russ
} >
} > You are making a RAID1+RAID0 array.
} > Try making a real RAID10 array with 4 drives.  This way you would only
} have
} > 1 array with 4 drives.
} >
} > >From the mdadm man page:
} > Currently, Linux supports LINEAR md devices,  RAID0  (striping),  RAID1
} >        (mirroring), RAID4, RAID5, RAID6, RAID10, MULTIPATH, and FAULTY.
} >
} > Notice RAID10 is listed, use that.  Man mdadm for more info.
} >
} > However, I would (and do) use RAID6.  With RAID6 any 2 disks can fail
} > without data loss.  With RAID1+RAID0, any one disk can fail, a second
} > failure has a 1 in 3 chance of vast data loss.
} >
} > I hope this helps,
} > Guy
} >
} > -
} >
} 
} 
} Guy,
} 
} That's what I've been trying to do.  Unfortunatelly, my distro, CentOS 5
} (based on RHEL 5, I believe), does not have the RAID10 personality in
} the kernel.  I guess I would have to compile my own kernel and load the
} module through a driver disk.  Would that work?  Are there some
} instructions somewhere I can follow?
} 
} Russ

I don't know how to make a driver disk.  Also not much on making modules.
From what I know, linux only loads the RAID modules it needs.  My system
does not have raid0 or raid10 loaded.  But both loaded when I used modprobe.
I have FC6, upgraded from FC5 using yum, so maybe not 100% FC6.

Anyway, you were not making a RAID10 array.  You were making 2 RAID1 arrays
and then 1 RAID0 array.  That does not need the RAID10 module (AFAIK).

If I recall, there is an issue of nesting arrays like you were doing.  The
problem was related to auto starting them.  But I don't recall any details,
and maybe it has been corrected.

Guy