Static SRDF and Dynamic SRDF

Hi Sid,

Static and Dynamic SRDF are very much what they sound like. But Static isn't quite as bad as what you are thinking.

Static SRDF is the "traditional" way of configuring things. You don't have to plan ahead before turning the arrays on for the first time, but configuration (and reconfiguration) does require EMC to do a BIN load on your arrays. This is sort of non-disruptive (although the required config locks can be somewhat disruptive to operations). It does require more planning ahead than Dynamic SRDF.

Dynamic SRDF allows you (the customer) to configure your own SRDF links and modify configurations without EMC's involvement. This works out very well if you have staff that understand SRDF and can plan and implement the configuration changes safely.

In our environment Some DMX3 (5773) and VMax (5784) arrays we exclusively use dynamic SRDF and it works well for us.

Hi Allen,

Glad to see your reply.

Now I got better understanding about SRDF

I understand that we can configure/reconfigure the static SRDF mirrors after Symmetrix is configured and runing in the production. This involves EMC to reload the BIN file in Symmetrix.(which is some what Non Distruptive)

Dynamic SRDF are more flexibile, Then why EMC still supports static SRDF .... What are the advantages of using Static SRDF.

Are we missing any point here ?

Thanks in advance,

Sid

I afraid I can't really comment on the advantages of Static SRDF other than to say that it may be useful in environments that have some kind of rigid configuration rules that make it better to put the control out of the hands of the day to day admins. That's just conjecture though.

Does anyone else have a better grasp on any advantages that Ststaic SRDF may offer over Dynamic?

Hello Sid/Allen,

I am certainly no SRDF Guru, however, following your question, I became curious (curious because I do have experience with other remote replication products such as those supported by some UNIX kernels, and also Sun StorEdge/STK and EMC RecoverPoint).

I did some digging around and this is what I found.

As we know, when products are released they have a defined Road Map to new features and functions. Symmetrix is no different here. Prior to Enginuity 5568 SRDF configuration was limited to 'static' configuration, meaning that it was done at the initial Symmetrix configuration time via the bin file created and delivered by EMC. One of the new features of Enginuity 5568 was the ability for the customer to configure their own SRDF pairs when the Symmetrix array is in production. Of course, this new feature required a technical marketing name, and so it was called Dynamic SRDF.

Whether we use static or dynamic, both will require similar careful planning. However, the additional advantages of dynamic are that the customer can create and manage their SRDF pairs whilst the Symmetric array is in operation; the customer is effectively given control of their SRDF configuration (no need to request a new bin file from EMC). The commands for doing this are detailed in the Solutions Enabler SRDF CLI guide.

Thanks, Richard.

Hi Sid - did these responses answer your questions?

Hello all,

actually there are no advantages of static SRDF over dynamic SRDF.

Static SRDF was the first SRDF solution available and required the configuration changes being made by EMC (through implementing a new bin file).

Starting 5671 code a static SRDF pair can be converted into dynamic SRDF.

By using dynamic SRDF your configuration is more flexible and can be changed "on the fly" by adding or removing remote mirrors.

Dynamic RDF is the default SRDF configuration starting with 5874 code.

Please see the EMC® Solutions Enabler Symmetrix® SRDF® Family CLI Product Guide for more details.

I hope this helps.

Cheers,

Eike

While I understand you point I would still hesitate to say that there are "no advantages" of Static over Dynamic. You could safely say there are "no technology advantages".

Process wise I think there are still customers out there who are better off with Static. If they don't have in house resources who understand the Symm and SRDF well enough they could get themselves into trouble with Dynamic SRDF without even realizing it. Static allows for an extra level of technical sanity check on what is being done.

That being said, I have no interest in Static in our environment, and I would hope that most customer sites implementing Symmetrix and SRDF would want trained, experienced, Proven resources available for both day to day maintenance and planning and configuration.

Allen,

do not get me wrong, but I see mainly disadvantages in using static SRDF.

One point is that you cannot easily (or let's say in a short time window) swap your device pairs. It can take a very long time, which is one of the reasons why static SRDF and personality swaps are not supported with EMC Cluster Enabler. Even the FAST Swap feature (failover -establish) does not work.

Cheers,

Eike

Hi All,

I see there are advantages of dynamic over static because of its flexibility.

Definitely, end user will have ability to configure with dynamic than in static

My question is answered :-)

Thanks All

Sid