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ymg800

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if i mount VMFS in the DR site, can i continue to replicated this LUN to the DR?

Hi

we are working in a DR project, with limeted budget for that matter.

i replace old admin and i am new at the job.

there are one v-center at the HQ  and one at the DR site

the VMFS (3 and 5) of VMware are replicated using Replication manager via EMC clarion storage.

there is no SRM product.

the old admin told me that if i mount the replicated VMFS LUN in the DR site (to test if all ok), i will no longer be able to replicated the LUNS to the other site sine the parrallel LUN in the other side will be "locked" and no incremetal replication can occure in the matter.

it that true?
is there away to continue to replicated the changes eche night will the VM are up and running at the other side? (to know the replication is ok)

using replication manager and clarion and i mentioned.

thanks.
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Duncan Meyers
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The answer is yes and no.

No - once you split the replicated LUNs to test them, replication must stop. Depending on the replication technology you're using (MirrorView, SANCopy, RecoverPoint - note that Replication Manager is a management and orchestration tool, not the replication method), you may be able resume only what's changed since the split, or restart the replication from the beginning.

But Yes! You can do what you want to do. You can create a clone of the replicated LUN at DR, split that off and test until your heart is content. Once you're done, you just delete the clone. Meanwhile, replication has continued and your production data is protected. You can automate the whole process in Replication Manager to make your life easier.
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ymg800

ASKER

sorry but i didnt quite get it, if i dont use clone, and use the "original" LUN, how whould i know if i need to create new luns for replication? will the job fail in RM?

thx
> if i dont use clone, and use the "original" LUN, how whould i know if i need to create new luns for replication? will the job fail in RM?
If you want to use the mirror LUN, then you will have to fracture the replication relationship, which will then allow you to mount the LUN on a server and access it. So if you don't have a step in the RM job to fracture the LUN, then the RM job will fail as the server can't access the LUN.

You are correct also in saying that replication stops while the LUNs are fractured unless you are using RecoverPoint as the replication technology. If you are using MirrorView/A or /S, you have to do a full resynchronisation, If you are using RecoverPoint, you synchronise the changes only. Alternatively, if you are using MirrorView/A or /S, you would create a clone of the mirror at the DR side, split that off for backup or testing. Meanwhile, replication continues to the DR side while you test on a copy of that data. Once you're finished testing with the clone, you can either discard it, or keep it as a point-in-time copy for quick recovery.
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ASKER

well i using san copy with RM without recovery point,
can u please a just your scanario according to that ?
SANCopy and MirrorView/A are basically the same thing, so you can interchange MirrorView/A and SANCopy in my response above.

Do you have SnapView on your array?
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hi

i dont have snapview or mirrorview, only sancopy.

so i didnt get it, if i will mount the LUN in the other side

1. will it be correupted? can replication continue with this spefic LUN?
2. does replication mamager check the LUN in the other side? will it alert me if replication cannot continue?
1. will it be correupted? can replication continue with this spefic LUN?
If you use Replixation Manager to handle the split, then no. It will not be corrupted. Replcation Manager can quiesce (pause) I/O on the host while it does the split, so the replicated LUN is in a consistent state. Note that Replication cannot continue while the SANCopy session is split.
2. does replication mamager check the LUN in the other side? will it alert me if replication cannot continue?
Yes to both questions provided the job has been set up to do that. It has quite granular alerting including email, paging and so on
Just to underline the point - if you split the SANCopy session, then you must restart it from the beginning. You can't do a partial resync.
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ASKER

can u please define "split"? sorry i a newby

so u saying that in the lun in no good for replication, replication manager will restart the replication will inital copy?

doent mouting the lun for just one second will corrupt the LUN? if yes what will replication manager will "tell" me?

thanks
>can u please define "split"? sorry i a newby
No problem. 'Split' means to separate the SANCopy target (the copy) from the source - this is also called an 'Administrative Fracture'. Once you've split the copy off from the source, you have to copy the whole LUN again. You can't just resync the changes, unfortunately., RecoverPoint will let you just resync changes, however.

>so u saying that in the lun in no good for replication, replication manager will restart the replication will inital copy?
Depends on how the Replication Manager job has been configured, but typically, yes. RM would restart the SANCopy job.

>doent mouting the lun for just one second will corrupt the LUN? if yes what will replication manager will "tell" me?
No - it won't corrupt the LUN if you mount it at the remote side. If you were replicating, say Microsoft SQL databases, you'd split the LUNs, mount the copy and run DBCC.exe against the databases to confirm that you have a good replica. Replcation Manager will report if a consistency check succeeds or fails
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ASKER

thanks you very much! the answer was very usfull!

i still have one question about :

">doent mouting the lun for just one second will corrupt the LUN? if yes what will replication manager will "tell" me?
No - it won't corrupt the LUN if you mount it at the remote side. If you were replicating, say Microsoft SQL databases, you'd split the LUNs, mount the copy and run DBCC.exe against the databases to confirm that you have a good replica. Replcation Manager will report if a consistency check succeeds or fails"


But what if i dont split the LUN , and i use the original replica of the source LUN in the DR  site?
(meanning , the lun in the DR site that the data was replicated to this LUN, however i mount this LUN, not a "clone" , which i understand that this is the meanning of "spliting")

hence, when i will mount the LUN, then two of the following question arises:

1. when the LUN is mounted, someone told me that i wont be able to continue the replication since the LUN will be Locked while mounted and the replication will fail to that LUN.

2. someone else told me, that if i mount the LUN in the other side, in read/ write mode, then the LUN can be change, and when i continue replication the replication can be unconsistent since replication manager "doent check" what was changed in the other side, it's make it's replication based on the files / blocks that was change since the lask replication, without exctually checking the destination LUN in the other side (the lun in the DR), is that true?

that again for the comprehensive answers
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Duncan Meyers
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Thanks! Glad I could help.
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ASKER

u did ! very much, excelet answer

by the way i read in EMC white papar the u dont need to splite the replica using san copy in order to write to the lune, only in mirrorview (regarding my other post)....
 so still can figure it out why the lun mounted in read only mode
Could you privude a link to the white paper and page number? Because I'm pretty sure that's incorrect. A replica (SANCopy, MirrorView or RecoverPoint) is 100% not writeable while the replication is running.
That means that the server can access the replicated data as read only and that you use a SnapView snapshot or clone to provide read/write access to the LUN.

If you split the replication, you'll be able to access the data for both read and write. But you will then need to re-replicate the entire LUN.
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ASKER

ok got it.

but how do i splite replication? the no "fructure" button like in clonning, only stop and delete  session.

will button in unispheare should i use? (silly question but still need to know...)

thank you!!
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ASKER

and forgot another question, how can i do that from the DR site? you cant see the san copy session from there...