anoopcr
3 Argentum

Question regarding Remote Mirror setup

Jump to solution

Hi,

I am in process of setting up DR for 1 server using remote mirror using mirror view.I have setup the remote mirror in async mode.2 LUNs are consistent now and 2 are in synchronizing mode.

Now I have to present the DR LUNs to ESX servers.But the ESX admin saying that when they create datastore,the LUN will get formatted.So i want to know how can i proceed fro here.

my thought is

1. fracture the seconday mirror

2.present the LUn to DR server

3.Once the datastore has been created and can synchronize it

can somebody tell this the correct ptocedure.I didnt do the these procedure before.and if there is any update to DR mirror(secondary),will that get copied to primary mirror

Thanks in advance

its a CX4 120

Labels (1)
0 Kudos
1 Solution

Accepted Solutions
JonK1
3 Zinc

Re: Question regarding Remote Mirror setup

Jump to solution

Yes, in that case you would promote the secondary image and add it to the storage group with the DR host. Then rescan and follow ksp's procedure:

ksp wrote:

3. ESX still won't automatically mount this new primary volume right away, because it is on a different storage and has different address, and it gets detected as a snapshot. Now you have to:

a) Make sure that the original Vol1 isn't and won't be accessible to ESX during the DR. It's ok if it is secondary now, or you have to disable access to it by other means.

b) Mount the new primary volume Vol2 using either resignature or temporary mount -- choose which is more appropriate for your situation:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=101138...

We use temporary mount with esxcfg-volume -m in our tests, because we put everything back shortly after. (Caution: there was a bad experience with persistent mount esxcfg-volume -M, we had to reboot all ESX hosts to get the volume back, just a heads-up for you)

View solution in original post

0 Kudos
12 Replies
pinnas
3 Zinc

Re: Question regarding Remote Mirror setup

Jump to solution

Hi Anoop,

May I know if both the Arrays are CX4 120’s , and also let us know FLARE release for both the arrays.

Regards,

Suman Pinnamaneni

0 Kudos
anoopcr
3 Argentum

Re: Question regarding Remote Mirror setup

Jump to solution

Hi Suman,

Yes.Both arrays are CX4 122. FLARE revision is 4.29.000.5.014 on both sides.

0 Kudos
anoopcr
3 Argentum

Re: Question regarding Remote Mirror setup

Jump to solution

correction : CX4 120..Typo error

0 Kudos
pinnas
3 Zinc

Re: Question regarding Remote Mirror setup

Jump to solution

Hi Anoop,

As per my knowledge, Once you fracture the Mirror and do some changes in the secondary mirror(LUN) and once you re-sync the mirror, the changes that you made in the secondary mirror(LUN) will not have any impact on the primary mirror(LUN)., and it only sync’s the data from the primary mirror(LUN) to the secondary mirror(LUN).

Any inputs here ……

Regards,

Suman Pinnamaneni

0 Kudos
etaljic81
4 Beryllium

Re: Question regarding Remote Mirror setup

Jump to solution

When you present the target LUN to the ESX server(s) you will need to click on the Add Storage button in ESX. You will be asked whether you want to re-signature the LUN. Select Yes. The data will not be erased on the LUN.

0 Kudos
anoopcr
3 Argentum

Re: Question regarding Remote Mirror setup

Jump to solution

Hi,

My ESX admin saying whenever he is trying to create a datastore using the replicated LUN,it showing as "The hard disk is blank"

am not familiar with these steps..can you tell me the step by step ? That will really helpful for me

0 Kudos
etaljic81
4 Beryllium

Re: Question regarding Remote Mirror setup

Jump to solution

That's because he hasn't selected to re-signature the volume when he adds the datastore. When he goes to add the VMFS datastore tell him to choose the re-signature option.

0 Kudos
anoopcr
3 Argentum

Re: Question regarding Remote Mirror setup

Jump to solution

Hi All,

ESX admin says,if this is  a VMFS labelled LUN,then only we will get re-signature option.I am not sure.Here the screen shot that he provided.

$B72C69C5CD015AD.bmp

I just want to clarify few things here.

I am basically from symmetrix background..In symmetrix we will use SRDF to setup the DR and we can use the target LUN during disaster for resuming the application.But in Clarrion is it possible to use the same remote mirror LUN for same purpose,I read few docs related to Mirror view and its  taking a snapshot of the remote mirror and provide to host during disaster..Is that mean we cant directly provide the target LUN to host ?

0 Kudos
JonK1
3 Zinc

Re: Question regarding Remote Mirror setup

Jump to solution

Anoop,

What version of ESX are you running? I can recall you had to change an advanced setting in ESX 3.5; i'm not sure if this is still necessary on ESX4/5.

The full procedure to build a DR environment is as follows. You've already done some of the steps, so skip those where appropriate:

Set up the environment:

- Create two identical LUNs, one on the primary system, one on the secondary.

- Make sure MirrorView is correctly configured (MirrorView Connections established etc).

- Create a mirror on the primary system.

- Add the secondary image using the LUN on the secondary array. Make sure you keep the "Initial Sync" button checked, otherwise you'll have garbage on the target LUN.

- Wait for the state of the secondary image to change from "Synchronizing" to either "Synchronized" or "Consistent" (this depends on whether there is still I/O going to the primary LUN; if the LUN is still used, Consistent is the best you'll get...).

Once this is in place, you can be pretty certain that your data is mirrored.

Now, to do a DR test or a failover, the following steps have to be taken:

- Fracture the mirror. This stops the sync.

- Promote the secondary image. This enables it for host I/O.

- Add the secondary image to a storage group. Make sure your primary image is NOT allocated to the same ESX host though, or your ESX host will get very confused.

- Rescan. Previously, if you had the resignature setting ENABLED, you would see your datastores pop up again with some sort of <originalname>-snap title.

- Or, as per Ernes a couple of posts above, use the "add storage" button in the later versions of VMware.

The above steps are for an actual failover. The downside here is that, after a promote your secondary image, it's now your production LUN. So to get back to your initial situation, you now have to:

- Reverse the mirror (basically, recreate it)

- stop host I/O to gracefully fallback

- again fracture and promote -> production is now at it's old location.

- Again, recreate your mirror.

So this takes lots of time and pushes gigantic amounts of data across your links, since each time you have to do an initial sync (you lose your logs with each promote).

For a simple DR test, you can also fracture the mirror (to stop the I/O to the secondary image), but NOT promote the secondary image. Instead, utilize SnapView to create a snap of the secondary image. This snap is now accessible for host I/O and can be added to a storage group. Do your testing. Afterwards, remove the snap and restart your mirror: it should pick up where it left.

(Or you can even NOT fracture it, but then you need quite a large RLP depending on the mirrored workload).

Hope this makes sense.. if you have any questions, don't hesitate!