Re: MIGRATING LUN IN AN A-A CLUSTERED FILERS

NAYABRASOOL · ‎2012-09-20

Hello Experts,

We have LUN a which needs to be moved from one filer to another filer can anybody help me out how to perform this do i need to have a LUN created already at the destination filer of same size or larger to migrate please help me with detailed steps.

Note :- Both the filers are in A-A CLUSTER mode and are FAS2040 now please let me know how i am gonna proceed on this .

Thanks,

Nayab

hmuellerpuma · ‎2012-09-20

Hi Nayab,

use Snapmirror to do this. just did it with a 7 TB LUN ....takes a while so be patient 🙂

kuber · ‎2012-09-20

Yes, as hmuellerpuma said please use snapmirror.

Can you please tell :

1. Is it an iSCSI or FC LUN? Wont make any difference when doing snapmirror.

2. What is this LUN currently used for? Is it used by an Application like exchange etc..?

hmuellerpuma · ‎2012-09-21

This is a FC LUN. correct...there is no difference.

but as larger as the lun is, as longer takes the delta.

the LUN is used for a Laptop Backup System.

funny thing is, i managed it to mirror from a 32 to a 64 bit aggregate 🙂

kuber · ‎2012-09-21

Thanks hmuellerpuma...

so Nayab... Can you also tell :

1. Is it an iSCSI or FC LUN?

2. What is this LUN currently used for? Is it used by an Application like exchange etc..?

hmuellerpuma · ‎2012-09-21

Actually, does it really matter if this is an iSCSI or FC LUN ? and does it really matter which application is using that ?

Snapmirror is volume based so this copies everything below a volume...doesnt matter if its files of a LUN ( which is actually a file in the Volume )

so more important would be giving more information how to do that, limitations and their workaraounds like no mirror from a 32 to a 64 bit aggregate.

and the workarround is a qtree snapmirror.

JWHITE_COMPUNET · ‎2012-09-21

Knowing the protocol is key for the migration. SnapMirror doesn't configure zoning or igroups.

hmuellerpuma · ‎2012-09-21

Thats true... but i assume that Nayab is aware of this...He wrote "We have LUN a which....."

So do you agree that if he already has a LUN that this might be already in use and an igroup was already created for this LUN and this igroup was already MAPPED ?

I think he also ZONED it on the FC Switches 🙂

Otherwise this request would be senseless... unused LUN ...empty ...moving ??? doesnt make any sense...or do you disagree ?

If it would be unsued, i would create a new Volume/LUN on the other Filer and delete the old one 🙂

So the point is that he has to snapmirror that (if he has the License to do so) and has to do the prerequisites as described in several tecnical documents.

To be exactly , we have to ask if he has a Snapmirror Licence and if not, to ask if he could unmap the LUN so that this could stay in an unaccessed state fer a certain time

(depends on the size) so he would have the option to use vol copy or ndmpcopy.

Thats the think we have to ask....not if this is an iSCSI or FC LUN.

🙂

kuber · ‎2012-09-22

Hi .. we are here to help people and not to point fingers on what should or shouldn't be asked... Some of the things you have said in your comments don't even make any sense to me.

Coming back to point:

: can you please tell us:

1. Is it an iSCSI or a FC LUN? There is "NO" principle difference in the method of snapmirroring any of these across to the destination. I just want to understand the design here.

2. Is the LUN being using by any application like exchange or oracle? - If yes, then you "can't" simply start the snapmirror. Snapshots is the very basis of snapmirror. When you start the snapmirror, a snapshot is taken of the Source. Having the LUN used by any applications I mentioned, wont give you a consistent copy of snapshot. You need to Quiece the I/O before you start the snapmirror. There are many ways to achieve this.

Explain us a bit about the current senerio and we will help you with the steps. Also to help yourself... be prepared to answer questions that people may ask you... this helps them in better understanding your problem/requirement.

@All: There are multiple method of achiveing the same thing... Just because you dont know ...doesn't mean it can't be done that way.

Cheers

hmuellerpuma · ‎2012-09-22

Okay, I am not pointing fingers to anyone but bringing it back to the topic.

Some of the things doesn't make sense to you ? Which things ?

A snap mirror to another filer makes a snapshot ????

Ever observed the transfered data and time when initiated a snapmirror ? Or updated it?

It fully copies over the data and not only a snapshot.

What you say is not true.

Indeed, what you say about the consistency is true.

A snapmirror done on a lun with a database in access is not consistent and not really useable.

So of course the lun must not be in access but only just before you do the last steps before breaking the mirror.

Best thing would be, stopping the database and disable the host side port(s) on the fc switch, then quisece it (means actually last delta will be written where lun io is stopped) and then break the mirror.

Don't forget to change the lun serial of the new lun.

Create Igroup (iscsi or fc), map it and change the zoning fitting to the destination filer. If it is the cluster partner, it should be already zoned before.

What you say about that you can't start a snapmirror while a lun is in access, yes you can and this usually done if you want to copy over a lun to another filer. Just think of a 15 TB LUN to copy over.

Think about how long it takes and that's the way how this is done. As said above, only the last delta must be copied over after the application was shut down properly and the lun is not in access.

8 years of netapp experience proves that what I write.

Greetings

Best regards

Hermann Mueller

Senior Administrator Linux & Storage

Puma SE

Wuerzburger Str. 13

91074 Herzogenaurach

Tel: +499132 812415

Fax: +499132 8142415

Cell: +49151 14743929

kuber · ‎2012-09-22

.. thanks for the reply... Can you please tell what exactly do you mean by "It fully copies over the data and not only a snapshot"... please explain the mechanism on which the snapmirror works? --> according to you.

Also I think you didn't get my point about quiecing the I/O's ... i never said "you can't start a snapmirror while a lun is in access"... I said " you "can't" simply start the snapmirror."... 'simply' is the key word here... if you understand what I mean.

Lastly, if experience is the criteria then I think I am by far more correct than you... But again I don't think that way ...as a guy with less experience than me... might know more than me! Knowledge is nowhere related to age/work experience !

Nayab: mate.. as you are not replying should we consider this resolved at your end?

Cheers

hmuellerpuma · ‎2012-09-23

Kuber,

To be exactly, snapmirror initiates a snapshot of the source volume ( or qtree) and all data blocks referenced by this snapshot copy are transferred and written to the destination system.

What I wanted to say in my previous answer is that snapmirror does not only transfer the reference pointers.

So full data is copied over.

TR3446

TR3326 page 9 "How snapmirror sync works"

Okay, you are far more correct than I am.

So continue asking about LUN type as this is really important for a snapmirror

Cheers

Best regards

Hermann Mueller

Senior Administrator Linux & Storage

Puma SE

Wuerzburger Str. 13

91074 Herzogenaurach

Tel: +499132 812415

Fax: +499132 8142415

Cell: +49151 14743929

NAYABRASOOL · ‎2012-09-23

Hi all,

My lun is an iscsi lun mapped to a windows 2008 R2 host where MYSQL running on it and sorry guys if my question was not straight forward as i am a fresher i myself confused to convey this.....

i dont have SNAPMIRROR in my env to do this. please advise.what if i do a vol copy or ndmp copy to that volume will it copy the whole contents of OLD VOLUME to the NEW VOLUME including LUN on it as i have oly one LUN per VOLUME .

Experts please advise.

Thanks

Nayab

hmuellerpuma · ‎2012-09-23

Hi Nayab,

i am sure that kuber will tell you exactly how this can be done and gives you step-by-step instructions what to do.

As he is an Expert and works at NetApp, he should be able to help you.

Greetings

hmuellerpuma · ‎2012-09-28

Hi Nayab,

did kuber help you and told you how the LUN can be migrated ?

Just wondering that he did not reply to your update.

Greetings

NAYABRASOOL · ‎2012-10-04

Hi hmuellerpuma,

Yes kuber is yet to come back.

Thanks,

Nayab