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Need to create a cascaded business copy

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Derek Brown
Frequent Advisor

Need to create a cascaded business copy

Hi

I've looked at the manuals for this and I'm still confused. Hoping someone here can help me create a horcm config file that will allow me to create a cascaded BCV.

I've attached here our existing horcm0.conf and horcm1.conf . These files are working and in production so I need to be careful not to screw them up otherwise my head will be on the block !

Everything is happening within the same server (urrtw01b) so there is no need to consider any other servers here. horcm0.conf essentially defines the same sets of data 3 times (bcv1, bvc2, bvc3) and horcm1.conf defines the luns that this data is replicated to.

As you will know, you can only create 3 sets of L1 pairs so I've used up my limit. I now need to create a L2 pair (ie a cascade or leaf) which I need to be a copy of the BCV3 data. This is where I am stuck.

I think I may need to create a horcm2.conf to define this and maybe also make additions to horcm0.conf but I'm not sure. Could someone possibly amend and/or create me the entries I need in the horcm config files please then that will be enough for me to figure out the logic of how it works and also allow me to do the job! I'd be eternally grateful.

Here are the luns (CU:Ldevs) that have been allocated to me to create the cascade ; lets call it bcv4 for convenience :

09:00
09:01
09:02
09:03
09:04
14 REPLIES
Prashanth Waugh
Esteemed Contributor
Solution

Re: Need to create a cascaded business copy

Hi

Which storage you r using like xp10000,12000 etc

Reagrds
Atul

For success, attitude is equally as important as ability
Derek Brown
Frequent Advisor

Re: Need to create a cascaded business copy

Hi

XP12000

regards

Derek
Prashanth Waugh
Esteemed Contributor

Re: Need to create a cascaded business copy

Hi
For success, attitude is equally as important as ability
Prashanth Waugh
Esteemed Contributor

Re: Need to create a cascaded business copy

Hi ,

Pls check the doc it will give some idea.
you closed thethread .its solved or not.sorry I m not able to attachethe doc.
----------------------------------------
Cascade function
This function creates a second layer of volume pairs underneath the first layer of BC pairs. Pairs created
in the first and second layer are called cascaded pairs. Figure 12 illustrates cascaded BC volume pairs.
The first cascade layer (L1) is the original BC pair, consisting of one P-VOL (root volume) and up to three
S-VOLs (node volumes). In the second cascade layer (L2), the S-VOLs of the original BC pair function as
the P-VOLs of the L2 pairs, and each L2 P-VOL can have up to two S-VOLs (leaf volumes). This layering
scheme can create up to nine copies of one BC primary volume (P-VOL).
Every volume can have up to three Mirror Unit (MU) numbers associated with it. The MU number
designates a pair for which the volume is a member. The MU number is not the number of the pair, but
the number of the volume. A pair is made up of two volumes of which each pair member could have the
same or different MU numbers.
â ¢ MU=0 is the number of a volume for its first pair.
â ¢ MU=1 is the number of the same volume for its next pair.
â ¢ MU=2 is the number of the same volume for its third pair.
â ¢ The MU number of an S-VOL is always MU=0.
34 Business Copy XP (BC) for the Array
For Level 1 (L1) pairs, the root volume could have MU=0, MU=1, and MU=2. For L1 pairs, the associated
S-VOLs all have MU=0 because this is the first pair of which they are a member.
For the Level 2 (L2) pairs, the L1 S-VOLs are now all acting as L2 P-VOLs. Because they are already a
member of one pair, the next MU number for each of them is MU=1 for their first L2 pair and MU=2 for
their second L2 pair. For the S-VOLs associated with each of these pairs, the MU number is once again
MU=0 because this is the first pair of which they are a member.

Reagrds
atul



For success, attitude is equally as important as ability
Derek Brown
Frequent Advisor

Re: Need to create a cascaded business copy

Atulkumar

It's very nice of you to cut and paste a piece of a manual for me that describes the functionality of cascading business copies ; but that is not what I need.

I need to know the exact configuation changes/additions to the files I attached in my original post and also whether or not I need to create a new horcm2.conf file on top of my existing horcm0.conf and horcm1.conf files.

Can you provide this information please ?
thanks
Derek
Prashanth Waugh
Esteemed Contributor

Re: Need to create a cascaded business copy

Hi Derek,

When you are going to implement this change.
I am thinking on it how to achive this.

Reagrds
atul
For success, attitude is equally as important as ability
Derek Brown
Frequent Advisor

Re: Need to create a cascaded business copy

Hi,

Wednesday next week.

thanks

Derek
cjb_1
Trusted Contributor

Re: Need to create a cascaded business copy

Derek

I don't believe there is anything to stop you making another BC from one of your original copies providing the data doesn't change. You wouldn't need a horcm2.conf just amend the current horcm0.conf and horcm1.conf.

So, to horcm0.conf add:
stby2_bcv4 erp3-1 60188 0b:00 0
stby2_bcv4 erp3-2 60188 0b:01 0
stby2_bcv4 erp3-3 60188 0b:02 0
stby2_bcv4 erp3-4 60188 0b:03 0
stby2_bcv4 erp3-5 60188 0b:04 0

stby2_bcv4 urrtw01b horcm1

And horcm1.conf
stby2_bcv4 erp3-1 60188 09:00
stby2_bcv4 erp3-2 60188 09:01
stby2_bcv4 erp3-3 60188 09:02
stby2_bcv4 erp3-4 60188 09:03
stby2_bcv4 erp3-5 60188 09:04

stby2_bcv4 urrtw01b horcm0

We do something similar across multiple hosts.
Derek Brown
Frequent Advisor

Re: Need to create a cascaded business copy

Chris,

Thanks for that but unfortunately that type of config is not possible.

The rules of business copy creation state that you can only create 3 copies from the original. If you want more than that (a 4th in my case) then you have to use the cascade method i.e. take a copy from a copy.

So I'm trying to obtain the config changes I need to make/add to my existing config files to allow a cascaded copy. If you know how to do that then I'd appreciate your help.

Derek
cjb_1
Trusted Contributor

Re: Need to create a cascaded business copy

Derek

I'm trying to relate your problem with our environment. Copy of a copy is configured in the same horcm files, its just a matter of getting the MU#'s sorted out.

The copy should work for any one of you L1 copies but to amend my first post make the MU# for the source disks 1 not 0.

So, to horcm0.conf add:
stby2_bcv4 erp3-1 60188 0b:00 1
stby2_bcv4 erp3-2 60188 0b:01 1
stby2_bcv4 erp3-3 60188 0b:02 1
stby2_bcv4 erp3-4 60188 0b:03 1
stby2_bcv4 erp3-5 60188 0b:04 1

stby2_bcv4 urrtw01b horcm1

If you wanted a second copy of a copy you'd do:

stby2_bcv5 erp4-1 60188 0b:00 2



Derek Brown
Frequent Advisor

Re: Need to create a cascaded business copy

Chris

Thanks for your reply. Just to confirm as I dont want to overwrite any data !! Are you saying the added entries should be :

To horcm0.conf add:
stby2_bcv4 erp3-1 60188 0b:00 1
stby2_bcv4 erp3-2 60188 0b:01 1
stby2_bcv4 erp3-3 60188 0b:02 1
stby2_bcv4 erp3-4 60188 0b:03 1
stby2_bcv4 erp3-5 60188 0b:04 1

stby2_bcv4 urrtw01b horcm1

And horcm1.conf
stby2_bcv4 erp3-1 60188 09:00
stby2_bcv4 erp3-2 60188 09:01
stby2_bcv4 erp3-3 60188 09:02
stby2_bcv4 erp3-4 60188 09:03
stby2_bcv4 erp3-5 60188 09:04

stby2_bcv4 urrtw01b horcm0

?
If so , ot seems a little unusual as MU = 1 has already been used in horcm0.conf and the luns you refer to don't exist. Or am I picking you up incorrectly. Sorry to be so pedantic, just I dont want to overwrite any data anywhere.

Thanks
Derek


cjb_1
Trusted Contributor

Re: Need to create a cascaded business copy

Always best to triple check these configs.

MU 1 was used to define the second of your L1 copies from the primary luns. We now want to define the copy of a copy. Cant use 0, this is assigned to the L1 copy from which we want to take the replica so next available is 1.

The luns i describe exist with the correct data once the business copy has completed. For this reason, when you schedule this up, you obviously have to ensure the business copy described in stby2_bcv1 completes prior to running bcv4.

As far as overwriting data goes that is something to check before you create the pair. The key here is to get the vector remote/local switch the right way round.

Derek Brown
Frequent Advisor

Re: Need to create a cascaded business copy

Chris

Thanks for your help but I'm totally confused now. Sorry for being so dull over this. It's just it looks like you are asking me to use luns that I've never mentioned and dont have (0b:00, 0b:01, etc); and also, I've already used MU 0,1 and 2 in horcm0.conf (source data) yet it looks like you are asking me to use MU 1 in horcm0.conf again! or am I misunderstanding you. Basically the cascade needs to copy from :
stby2_bcv3 erp2-1 60188 0c:42
stby2_bcv3 erp2-2 60188 0c:43
stby2_bcv3 erp2-3 60188 0c:44
stby2_bcv3 erp2-4 60188 0c:45
stby2_bcv3 erp2-5 60188 0c:46

to:
stby2_bcv4 erp3-1 60188 09:00
stby2_bcv4 erp3-2 60188 09:01
stby2_bcv4 erp3-3 60188 09:02
stby2_bcv4 erp3-4 60188 09:03
stby2_bcv4 erp3-5 60188 09:04

Can we start again please. Can you explicity show the additions that are required to the horcm files including the MU numbers please ?

Also , in order to create the initial L1 pairs I used (with HORCMINST=0):
paircreate -g stby2_bcv1 -vl
paircreate -g stby2_bcv2 -vl
paircreate -g stby2_bcv3 -vl

Now, in order to create the L2 cascade do I simply use :
paircreate -g stby2_bcv4 -vl

Many thanks, and apologies for all this long windedness.

Derek

cjb_1
Trusted Contributor

Re: Need to create a cascaded business copy

Derek

I was looking at the horcm files you attached to the post. Those luns are associated with the first of you business copies?

You config is equally as valid, you will be using the 3rd set of disks, add the '1' to the end of the line and you'll be fine.

The paircreate looks fine too.

So for your changes:
To horcm0.conf add:
stby2_bcv4 erp3-1 60188 0c:42 1
stby2_bcv4 erp3-2 60188 0c:43 1
stby2_bcv4 erp3-3 60188 0c:44 1
stby2_bcv4 erp3-4 60188 0c:45 1
stby2_bcv4 erp3-5 60188 0c:46 1

stby2_bcv4 urrtw01b horcm1

And horcm1.conf
stby2_bcv4 erp3-1 60188 09:00
stby2_bcv4 erp3-2 60188 09:01
stby2_bcv4 erp3-3 60188 09:02
stby2_bcv4 erp3-4 60188 09:03
stby2_bcv4 erp3-5 60188 09:04

stby2_bcv4 urrtw01b horcm0