Mailing List Archive: DRBD: Users

Switch from MD to DRBD

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pierpaolo.fasano at coritel

Mar 16, 2012, 5:32 AM

Post #1 of 9 (486 views)
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Switch from MD to DRBD

Hi,
I'm in the middle of switching from a software RAID1 based on MD to another one based on DRBD but using the same disks.
I've verified that no data loss occurs during this operation, but I'm wondering if it's possible to avoid the initial full synchronization between disks since I'm sure the two disks are already mirrored by MD.
Is it possible to achieve it and in which way?

Thanks in advance!

Regards,
Pierpaolo

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florian at hastexo

Mar 16, 2012, 6:27 AM

Post #2 of 9 (471 views)
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Re: Switch from MD to DRBD [In reply to]

On Fri, Mar 16, 2012 at 1:32 PM, pierpaolo.fasano
<pierpaolo.fasano [at] coritel> wrote:
> Hi,
> I'm in the middle of switching from a software RAID1 based on MD to another one based on DRBD but using the same disks.
> I've verified that no data loss occurs during this operation, but I'm wondering if it's possible to avoid the initial full synchronization between disks since I'm sure the two disks are already mirrored by MD.
> Is it possible to achieve it and in which way?

http://www.drbd.org/users-guide-8.3/s-using-truck-based-replication.html

Cheers,
Florian

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jsmith at argotec

Mar 16, 2012, 6:36 AM

Post #3 of 9 (469 views)
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Re: Switch from MD to DRBD [In reply to]

----- Original Message -----
> From: "pierpaolo.fasano" <pierpaolo.fasano [at] coritel>
> To: drbd-user [at] lists
> Sent: Friday, March 16, 2012 8:32:03 AM
> Subject: [DRBD-user] Switch from MD to DRBD
>
> Hi,
> I'm in the middle of switching from a software RAID1 based on MD to
> another one based on DRBD but using the same disks.
> I've verified that no data loss occurs during this operation, but I'm
> wondering if it's possible to avoid the initial full synchronization
> between disks since I'm sure the two disks are already mirrored by
> MD.
> Is it possible to achieve it and in which way?

Not sure this is the right answer without further information about your setup - what you have and where you're headed (you have 2 disk MD RAID 1... and are moving one of the disks to a new server? going to have DRBD on top of MD?) but...

You should be able to add the the meta data to the existing array with something similiar to this:
http://lists.linbit.com/pipermail/drbd-user/2009-February/011464.html

Then removed the mirror drive and do a "truck-based" replication explained here - specifically appropriate case listed under #2:
http://www.drbd.org/users-guide-legacy/s-using-truck-based-replication.html

HTH

Jake
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jsmith at argotec

Mar 16, 2012, 6:38 AM

Post #4 of 9 (470 views)
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Re: Switch from MD to DRBD [In reply to]

Florian beat me to it!

He has those links on speed dial :-)

Jake

----- Original Message -----
> From: "Florian Haas" <florian [at] hastexo>
> To: "pierpaolo.fasano" <pierpaolo.fasano [at] coritel>
> Cc: drbd-user [at] lists
> Sent: Friday, March 16, 2012 9:27:00 AM
> Subject: Re: [DRBD-user] Switch from MD to DRBD
>
> On Fri, Mar 16, 2012 at 1:32 PM, pierpaolo.fasano
> <pierpaolo.fasano [at] coritel> wrote:
> > Hi,
> > I'm in the middle of switching from a software RAID1 based on MD to
> > another one based on DRBD but using the same disks.
> > I've verified that no data loss occurs during this operation, but
> > I'm wondering if it's possible to avoid the initial full
> > synchronization between disks since I'm sure the two disks are
> > already mirrored by MD.
> > Is it possible to achieve it and in which way?
>
> http://www.drbd.org/users-guide-8.3/s-using-truck-based-replication.html
>
> Cheers,
> Florian
>
> --
> Need help with High Availability?
> http://www.hastexo.com/now
> _______________________________________________
> drbd-user mailing list
> drbd-user [at] lists
> http://lists.linbit.com/mailman/listinfo/drbd-user
>
>
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florian at hastexo

Mar 16, 2012, 6:55 AM

Post #5 of 9 (470 views)
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Re: Switch from MD to DRBD [In reply to]

On Fri, Mar 16, 2012 at 2:38 PM, Jake Smith <jsmith [at] argotec> wrote:
> Florian beat me to it!
>
> He has those links on speed dial :-)

I wrote them. :)

Florian

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pierpaolo.fasano at coritel

Mar 16, 2012, 7:34 AM

Post #6 of 9 (468 views)
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Re: Switch from MD to DRBD [In reply to]

Hi all,
thank you. It has seemed to me that the solution is to clear the bitmap and let DRBD consider data consistent on both disks.
Indeed I followed the steps showed in http://www.drbd.org/users-guide-8.3/re-drbdsetup.html and it works fine!

After I've disabled MD raid and configured DRBD resource based on the former raid disks I started drbd in this way:

1.On both nodes, initialize meta data and configure the device.
drbdadm -- --force create-md res

2.They need to do the initial handshake, so they know their sizes.
drbdadm up res

3.They are now Connected Secondary/Secondary Inconsistent/Inconsistent. Generate a new current-uuid and clear the dirty bitmap.
drbdadm -- --clear-bitmap new-current-uuid res

4.They are now Connected Secondary/Secondary UpToDate/UpToDate. Make one side primary and create a file system.
drbdadm primary res

Hoping this can help somebody else,
Cheers

Pierpaolo

----------------------------------------------------------------------

Da: "Florian Haas" florian [at] hastexo
A: "pierpaolo.fasano" pierpaolo.fasano [at] coritel
Cc: drbd-user [at] lists
Data Fri, 16 Mar 2012 14:27:00 +0100
Oggetto: Re: [DRBD-user] Switch from MD to DRBD

> On Fri, Mar 16, 2012 at 1:32 PM, pierpaolo.fasano
> <pierpaolo.fasano [at] coritel> wrote:
> > Hi,
> > I'm in the middle of switching from a software RAID1 based on MD to another one based on DRBD but using the same disks.
> > I've verified that no data loss occurs during this operation, but I'm wondering if it's possible to avoid the initial full synchronization between disks since I'm sure the two disks are already mirrored by MD.
> > Is it possible to achieve it and in which way?
>
> http://www.drbd.org/users-guide-8.3/s-using-truck-based-replication.html
>
> Cheers,
> Florian
>
> --
> Need help with High Availability?
> http://www.hastexo.com/now
>

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arnold at arnoldarts

Mar 16, 2012, 2:11 PM

Post #7 of 9 (462 views)
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Re: Switch from MD to DRBD [In reply to]

On 16.03.2012 14:38, Jake Smith wrote:
> Florian beat me to it!
> He has those links on speed dial :-)

You can also pay him. Then you can have his number on speed dial so he
reads the links (and their contents) to you:-)

Have fun,

Arnold
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jsmith at argotec

Mar 16, 2012, 8:42 PM

Post #8 of 9 (462 views)
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Re: Switch from MD to DRBD [In reply to]

----- Original Message -----
> From: "Arnold Krille" <arnold [at] arnoldarts>
> To: drbd-user [at] lists
> Sent: Friday, March 16, 2012 5:11:59 PM
> Subject: Re: [DRBD-user] Switch from MD to DRBD
>
> On 16.03.2012 14:38, Jake Smith wrote:
> > Florian beat me to it!
> > He has those links on speed dial :-)
>
> You can also pay him. Then you can have his number on speed dial so
> he
> reads the links (and their contents) to you:-)
>

^^^^^^^^^^^^^^^^^^^^^^^^
He should put that in his signature!

Jake
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florian at hastexo

Mar 17, 2012, 2:01 AM

Post #9 of 9 (461 views)
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Re: Switch from MD to DRBD [In reply to]

On Sat, Mar 17, 2012 at 4:42 AM, Jake Smith <jsmith [at] argotec> wrote:
> ----- Original Message -----
>> From: "Arnold Krille" <arnold [at] arnoldarts>
>> To: drbd-user [at] lists
>> Sent: Friday, March 16, 2012 5:11:59 PM
>> Subject: Re: [DRBD-user] Switch from MD to DRBD
>>
>> On 16.03.2012 14:38, Jake Smith wrote:
>> > Florian beat me to it!
>> > He has those links on speed dial :-)
>>
>> You can also pay him. Then you can have his number on speed dial so
>> he
>> reads the links (and their contents) to you:-)
>>
>
> ^^^^^^^^^^^^^^^^^^^^^^^^
> He should put that in his signature!

I realize this is all in jest and good humor, but just for the record
I'd like to point out that our remote consultancy services are *just a
wee bit* more comprehensive than reading documentation to people. :)

Besides, the way to reach me (or Martin, or Andreas) on "speed dial",
so to speak, already *is* in my signature.

Cheers,
Florian

--
Need help with High Availability?
http://www.hastexo.com/now
^^^^^
See? There 'tis. :)
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