Grow a RAID-10

Grow a RAID-10

[Daniel L. Miller]

I currently have a RAID10 across (4) SATA drives.  It looks like I'm 
going to need to grow in the near future.  Any tips for a procedure for 
this?  My current plan:

1.  Add a PCI SATA controller (MB had 4 SATA + 4 RAID SATA, it's a Tyan 
MB with a NFORCE chipset, I'm not sure if I want/can use the RAID SATA 
ports as plain SATA connections).

2.  Add 2 more drives - not necessarily the same size as the existing 
(they were all 4 the same)

3.  Execute "mdadm --grow /dev/md0"

-- 
Daniel

Re: Grow a RAID-10

[Keld Jørn Simonsen]

On Wed, Jul 02, 2008 at 02:56:04PM -0700, Daniel L. Miller wrote:
> I currently have a RAID10 across (4) SATA drives.  It looks like I'm 
> going to need to grow in the near future.  Any tips for a procedure for 
> this?  My current plan:
> 
> 1.  Add a PCI SATA controller (MB had 4 SATA + 4 RAID SATA, it's a Tyan 
> MB with a NFORCE chipset, I'm not sure if I want/can use the RAID SATA 
> ports as plain SATA connections).

Why not use the mobo raid sata ports? They are probably faster than a
controller on the pci bus. What kind of pci bus do you have?

PCI-E 1x is likely to be too slow for a 4-drive raid10,f2 array.
My 4-drive raid10,f2 delivers about 320 MB/s and newer disks should be
able to deliver 360 MB/s - well above the 250 MB/s that a PCI-E 1x can
deliver. 

> 2.  Add 2 more drives - not necessarily the same size as the existing 
> (they were all 4 the same)
> 
> 3.  Execute "mdadm --grow /dev/md0"

What kind of raid10 do you have?> 

Best regards
keld

Re: Grow a RAID-10

[Daniel L. Miller]

Keld Jørn Simonsen wrote:
> On Wed, Jul 02, 2008 at 02:56:04PM -0700, Daniel L. Miller wrote:
>   
>> I currently have a RAID10 across (4) SATA drives.  It looks like I'm 
>> going to need to grow in the near future.  Any tips for a procedure for 
>> this?  My current plan:
>>
>> 1.  Add a PCI SATA controller (MB had 4 SATA + 4 RAID SATA, it's a Tyan 
>> MB with a NFORCE chipset, I'm not sure if I want/can use the RAID SATA 
>> ports as plain SATA connections).
>>     
>
> Why not use the mobo raid sata ports? They are probably faster than a
> controller on the pci bus. What kind of pci bus do you have?
>
>   
My mistake.  Confused this one with another system.  Only have 4 ports 
available.  I did have the option of using the Nvidia RAID - which I did 
NOT enable.

What "kind" of pci bus?  Don't understand the question.  If it matters, 
it's a Tyan S2892, a "Thunder K8SE".  nForce Pro2200 and AMD8131 PCI-X 
chipsets.
> PCI-E 1x is likely to be too slow for a 4-drive raid10,f2 array.
> My 4-drive raid10,f2 delivers about 320 MB/s and newer disks should be
> able to deliver 360 MB/s - well above the 250 MB/s that a PCI-E 1x can
> deliver. 
>
>   
>> 2.  Add 2 more drives - not necessarily the same size as the existing 
>> (they were all 4 the same)
>>
>> 3.  Execute "mdadm --grow /dev/md0"
>>     
>
> What kind of raid10 do you have?> 
>   
I don't understand this question either.

mdadm --detail /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Tue Oct  3 19:11:53 2006
     Raid Level : raid10
     Array Size : 312581632 (298.10 GiB 320.08 GB)
  Used Dev Size : 156290816 (149.05 GiB 160.04 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Wed Jul  2 18:46:15 2008
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : near=2, far=1
     Chunk Size : 32K

           UUID : 9d94b17b:f5fac31a:577c252b:0d4c4b2a
         Events : 0.10941692

    Number   Major   Minor   RaidDevice State
       0       8        0        0      active sync   /dev/sda
       1       8       16        1      active sync   /dev/sdb
       2       8       32        2      active sync   /dev/sdc
       3       8       48        3      active sync   /dev/sdd

-- 
Daniel
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Re: Grow a RAID-10

[Keld Jørn Simonsen]

On Wed, Jul 02, 2008 at 06:47:31PM -0700, Daniel L. Miller wrote:
> Keld Jørn Simonsen wrote:
> >On Wed, Jul 02, 2008 at 02:56:04PM -0700, Daniel L. Miller wrote:
> >  
> >>I currently have a RAID10 across (4) SATA drives.  It looks like I'm 
> >>going to need to grow in the near future.  Any tips for a procedure for 
> >>this?  My current plan:
> >>
> >>1.  Add a PCI SATA controller (MB had 4 SATA + 4 RAID SATA, it's a Tyan 
> >>MB with a NFORCE chipset, I'm not sure if I want/can use the RAID SATA 
> >>ports as plain SATA connections).
> >>    
> >
> >Why not use the mobo raid sata ports? They are probably faster than a
> >controller on the pci bus. What kind of pci bus do you have?
> >
> >  
> My mistake.  Confused this one with another system.  Only have 4 ports 
> available.  I did have the option of using the Nvidia RAID - which I did 
> NOT enable.

Yes, it is fine not to use the two on-board raid controllers in raid
mode, but just to use SW raid on them. I have a similar mobo with 2
sata controllers and the ability to attach 8 sata drives, which I have
all been using to run SW raid, and I have not experienced any problems
yet with this setup.

I understand that your mobo has 4 onboard sata connections, and that
these are already in use for the current array.

> What "kind" of pci bus?  Don't understand the question.  If it matters, 
> it's a Tyan S2892, a "Thunder K8SE".  nForce Pro2200 and AMD8131 PCI-X 
> chipsets.

So it has both PCI-X bus and PCI-E bus. You want to attact 2 more drives 
and you need a sata controller. This could probably both be attached via
the PCI-X bus and the PCI-E bus. It seems like the PCI-X bus - with a
133 MHz possibility counld be the faster of the 2, but given you will
only have 2 more drives, both PCI-X and PCI-E are prossibilties.

> >PCI-E 1x is likely to be too slow for a 4-drive raid10,f2 array.
> >My 4-drive raid10,f2 delivers about 320 MB/s and newer disks should be
> >able to deliver 360 MB/s - well above the 250 MB/s that a PCI-E 1x can
> >deliver. 
> >
> >  
> >>2.  Add 2 more drives - not necessarily the same size as the existing 
> >>(they were all 4 the same)
> >>
> >>3.  Execute "mdadm --grow /dev/md0"
> >>    
> >
> >What kind of raid10 do you have?> 
> >  
> I don't understand this question either.
> 
> mdadm --detail /dev/md0
> /dev/md0:
>        Version : 00.90.03
>  Creation Time : Tue Oct  3 19:11:53 2006
>     Raid Level : raid10
>     Array Size : 312581632 (298.10 GiB 320.08 GB)
>  Used Dev Size : 156290816 (149.05 GiB 160.04 GB)
>   Raid Devices : 4
>  Total Devices : 4
> Preferred Minor : 0
>    Persistence : Superblock is persistent
> 
>    Update Time : Wed Jul  2 18:46:15 2008
>          State : clean
> Active Devices : 4
> Working Devices : 4
> Failed Devices : 0
>  Spare Devices : 0
> 
>         Layout : near=2, far=1
>     Chunk Size : 32K
> 
>           UUID : 9d94b17b:f5fac31a:577c252b:0d4c4b2a
>         Events : 0.10941692
> 
>    Number   Major   Minor   RaidDevice State
>       0       8        0        0      active sync   /dev/sda
>       1       8       16        1      active sync   /dev/sdb
>       2       8       32        2      active sync   /dev/sdc
>       3       8       48        3      active sync   /dev/sdd

I was takling about the layout, and you have a n2 layout (standard
raid10 - near=2). You may benefit from a raid10,f2 layout, as this has faster 
read capabilities, but I think it is not possible on the fly to
rearrange a raid10,n2 array to a raid10,f2 array.

Given that you have a raid10,n2 layout, the speeds of the busses are not
so important, as raid10,n2 cannot deliver that high performance. 
I would expect less than 100 MB/s coming out of your 2 extra disks.

What is the use for your raid? is it a database, a file server, a web
server or the like?

Best regards
keld
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Re: Grow a RAID-10

[Daniel L. Miller]

Keld Jørn Simonsen wrote:
> On Wed, Jul 02, 2008 at 06:47:31PM -0700, Daniel L. Miller wrote:
>   
>> Keld Jørn Simonsen wrote:
>>     
>>> On Wed, Jul 02, 2008 at 02:56:04PM -0700, Daniel L. Miller wrote:
>>>  
>>>       
>>>> I currently have a RAID10 across (4) SATA drives.  It looks like I'm 
>>>> going to need to grow in the near future.  Any tips for a procedure for 
>>>> this?  My current plan:
>>>>
>>>> 1.  Add a PCI SATA controller (MB had 4 SATA + 4 RAID SATA, it's a Tyan 
>>>> MB with a NFORCE chipset, I'm not sure if I want/can use the RAID SATA 
>>>> ports as plain SATA connections).
>>>>    
>>>>         
>>> Why not use the mobo raid sata ports? They are probably faster than a
>>> controller on the pci bus. What kind of pci bus do you have?
>>>
>>>  
>>>       
>> My mistake.  Confused this one with another system.  Only have 4 ports 
>> available.  I did have the option of using the Nvidia RAID - which I did 
>> NOT enable.
>>     
>
> Yes, it is fine not to use the two on-board raid controllers in raid
> mode, but just to use SW raid on them. I have a similar mobo with 2
> sata controllers and the ability to attach 8 sata drives, which I have
> all been using to run SW raid, and I have not experienced any problems
> yet with this setup.
>
> I understand that your mobo has 4 onboard sata connections, and that
> these are already in use for the current array.
>
>   
>> What "kind" of pci bus?  Don't understand the question.  If it matters, 
>> it's a Tyan S2892, a "Thunder K8SE".  nForce Pro2200 and AMD8131 PCI-X 
>> chipsets.
>>     
>
> So it has both PCI-X bus and PCI-E bus. You want to attact 2 more drives 
> and you need a sata controller. This could probably both be attached via
> the PCI-X bus and the PCI-E bus. It seems like the PCI-X bus - with a
> 133 MHz possibility counld be the faster of the 2, but given you will
> only have 2 more drives, both PCI-X and PCI-E are prossibilties.
>
>   
>>> PCI-E 1x is likely to be too slow for a 4-drive raid10,f2 array.
>>> My 4-drive raid10,f2 delivers about 320 MB/s and newer disks should be
>>> able to deliver 360 MB/s - well above the 250 MB/s that a PCI-E 1x can
>>> deliver. 
>>>
>>>  
>>>       
>>>> 2.  Add 2 more drives - not necessarily the same size as the existing 
>>>> (they were all 4 the same)
>>>>
>>>> 3.  Execute "mdadm --grow /dev/md0"
>>>>    
>>>>         
>>> What kind of raid10 do you have?> 
>>>  
>>>       
>> I don't understand this question either.
>>
>> mdadm --detail /dev/md0
>> /dev/md0:
>>        Version : 00.90.03
>>  Creation Time : Tue Oct  3 19:11:53 2006
>>     Raid Level : raid10
>>     Array Size : 312581632 (298.10 GiB 320.08 GB)
>>  Used Dev Size : 156290816 (149.05 GiB 160.04 GB)
>>   Raid Devices : 4
>>  Total Devices : 4
>> Preferred Minor : 0
>>    Persistence : Superblock is persistent
>>
>>    Update Time : Wed Jul  2 18:46:15 2008
>>          State : clean
>> Active Devices : 4
>> Working Devices : 4
>> Failed Devices : 0
>>  Spare Devices : 0
>>
>>         Layout : near=2, far=1
>>     Chunk Size : 32K
>>
>>           UUID : 9d94b17b:f5fac31a:577c252b:0d4c4b2a
>>         Events : 0.10941692
>>
>>    Number   Major   Minor   RaidDevice State
>>       0       8        0        0      active sync   /dev/sda
>>       1       8       16        1      active sync   /dev/sdb
>>       2       8       32        2      active sync   /dev/sdc
>>       3       8       48        3      active sync   /dev/sdd
>>     
>
> I was takling about the layout, and you have a n2 layout (standard
> raid10 - near=2). You may benefit from a raid10,f2 layout, as this has faster 
> read capabilities, but I think it is not possible on the fly to
> rearrange a raid10,n2 array to a raid10,f2 array.
>
> Given that you have a raid10,n2 layout, the speeds of the busses are not
> so important, as raid10,n2 cannot deliver that high performance. 
> I would expect less than 100 MB/s coming out of your 2 extra disks.
>
> What is the use for your raid? is it a database, a file server, a web
> server or the like?
>
> Best regards
> keld
>   

This is our all-in-one server.  The raid is the primary storage for 
everything - day-to-day operations files, quickbooks data, virtual 
machines.  O/S and programs are on a separate non-raid drive.
--
Daniel
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Re: Grow a RAID-10

[Robin Hill]

[-- Attachment #1: Type: text/plain, Size: 1171 bytes --]

On Wed Jul 02, 2008 at 02:56:04PM -0700, Daniel L. Miller wrote:

> I currently have a RAID10 across (4) SATA drives.  It looks like I'm going 
> to need to grow in the near future.  Any tips for a procedure for this?  My 
> current plan:
>
> 1.  Add a PCI SATA controller (MB had 4 SATA + 4 RAID SATA, it's a Tyan MB 
> with a NFORCE chipset, I'm not sure if I want/can use the RAID SATA ports 
> as plain SATA connections).
>
> 2.  Add 2 more drives - not necessarily the same size as the existing (they 
> were all 4 the same)
>
> 3.  Execute "mdadm --grow /dev/md0"
>
Unless something's changed very recently then you can't grow a RAID-10
array (by adding disks anyway) - only RAID-1, RAID-5 and RAID-6 can be
grown in this way.

If you do want to grow it then the process will have to be backup,
recreate and restore.  Otherwise you can set them up as a RAID-1 and
mount them as another filesystem.

Sorry,
    Robin
-- 
     ___        
    ( ' }     |       Robin Hill        <robin@robinhill.me.uk> |
   / / )      | Little Jim says ....                            |
  // !!       |      "He fallen in de water !!"                 |

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