Breaking Concurrent SRDF

Question

Hi Guys, Here is the story : We got a Migration between two Datacenters having DMX-3 and DMX-4 and we are asking EMC to use the bin load to create the relationship between the devices. Now we got three boxes for e.g SID 111(DMX-3) @ Site A , SID222 (DMX-2K) @ Site B & new DMX-4 SID 333 @ Site B. SID 111 is the box to be migrated to DMX-4, SID 111 contains the R1 & R5 devices and also some R2 devices for SID 222. Now we need to have concurrent srdf setup b/w SID 111 , 222 & 333. Once we have the relationship and we are ready to migrate the Host from Site A to Site B , I need to manually break the SRDF relationship, I need to know if we don't set the dynamic_rdf flag on the devices, since we are using bin load for creating relationships.Would i be able to break/spit the srdf relationship using symrdf ? If not, then what would be the best possible way out ? Scenario : SID111 -> R1 ->R2 (SID222) SID111 -> R2 -> R1 (SID 222) SID111 -> R5 All these devices on SID 111 has to be migrated to SID 333.

xe2sdc · Accepted Answer

Ahahahahah Don't worry Bhat ..You aren't testing my patience With dynamic rdf you can create and delete pairs. If EMC create and delete pairs with binfiles you don't need dynrdf.Once you have the pairs (either static/binfile or dynamic/symrdf) you can control the pairs (establish/split/suspend/resume/almost_whatever) using pairfiles instead of DGs

xe2sdc · Answer

Bhat I guess you simply need to break RDF copy (using symrdf suspend/failover commands). And leave EMC the burden to clean up static RDF pairs with another binfile just before dismissing source storage

xe2sdc · Answer

Bhat you need dynamic_rdf only if you want to create/remove RDF pairs. You don't need dyn_rdf if you have to failover/suspend/establish/resume/failback your existing pairs

Simply put R1 devices in a DG and manage the pairs using symrdf command (with an added twist as per emc101638).

StorageAdmin2 · Answer

Hey Stefano,
If we don't have the dymanic_rdf enabled on the devices, can we do the symrdf operations on the file (split/suspend/failover) ? or we need to have the devices in the device groups and then work with that ?I was of the view that, usinf file option won't work if we don't have dyn_rdf enabled , please correct me if i am wrong.

StorageAdmin2 · Answer

So you saying, even if EMC CE is doing the SRDF replication between the devices on two Boxes via bin load and not using dynamic_rdf, i still can run symrdf pair file for all srdf operations.

Just to be precise, we are not establishing the relatiohships using symrdf operation, but EMC would use the bin file load on two EMC DMX's with all necessary inforamation regarding R1 & R2. So all i have to do is the split/map and mask. I hope I am not testing your patience

xe2sdc · Answer

Oh BTW you can easily failover/suspend/failback/establish/split pairs using pair files.
I usually use DG like a "shortcut". Instead of typing the box, the DG and the pairs, I put everything in a DG and I can manage the pairs easily. But nothing stops you from using pairfiles.

symrdf -sid xxx -rdfg yy -file pairfile suspend/resume/failover/failback/establish/split/almost_whatever_you_want

StorageAdmin2 · Answer

Thanks for clarifying this for me

RRR · Answer

I love DG files. Since I learned about these files I stopped using device groups completely. Files can be copied for backup reasons and maintained as part of documentation. Device groups depend on the local database of the host SymCLI is running on.

StorageAdmin2 · Answer

I agree with what you say in terms of backing up the DG files , just that it is little pain to get the list of all the devices and put them in the file, that concerns me. If one makes a habbit of adding devices in DG at the start of provisioning, it makes things little simpler to operate

StorageAdmin2 · Answer

It would be great if you could share that excel script you talking about , I am not really good at scripts , i will send you a lovely Souvenir from India

RRR · Answer

Send me an email and we'll talk about it in more detail.

RRR · Answer

It works two ways o/c. If you're used to files, then DG's are a lot of work to keep current. I prefer files since you can easily create scripts in Excel and copy paste symdev numbers from spreadsheets.

xe2sdc · Answer

RRR you can always export DG to files and backup the export-files

Just like you do with your Oracle databases, you have to export data off the database and backup the export file. That's why we named it "symapi database"

RRR · Answer

I know, but normally you either choose for files or DG's.

StorageAdmin2 · Answer

I got another point here :I have got a DB servers accessing storage from one box and it's R2 on another box, now the team wants to swap the roles without enabling the dynamic_rdf. so is the below mentioned procedure ok :1. Split SRDF2. Write_disable the devices3. Unmap devices on both the ends.4. Convert to STD devices.5. Convert the same devices to R1 & R2 on each box.6. Map the devices7. Establish the devices using invalidate R2 option --> would this be ok or should i use acp_disk mode ? I hope the data won't be corrupted.8. Mask the devices.I just wanted to confirm that while doing all this, my data is safe and nothing happens to it ?Would appreciate if you could answer.

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Breaking Concurrent SRDF

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