anoopcr
3 Argentum

What will happen to SRDF/A delta set after the session drop due to max WP

Hi All,

Need a small clarification about SRDF/A

SRDF/A work depend upon the delta set concept.the data will store in symm cache for a particular time(delta set) and it will transfer to remote symm.If there is a high writes and if the delta set exceeds the max cache usage limit(94% in 5773 below and 75%5784 and above) the SRDF/A session will drop and rdfpair will go to suspended mode.

My question is if we didn’t resume group for a extended period of time,what will happen to the delta set because already there is no space in cache.So will the symm store new data in cache or will it destage to R1 disk

Thanks,

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sauravrohilla
4 Tellurium

Re: What will happen to SRDF/A delta set after the session drop due to max WP

HI Anoop,

The moment WP usage hits the WP limit, the SRDF/A session drops. This means the links would be suspended and all pending tracks on R1 will be marked invalid (R1 Symm will ONLY keep the information that these invalid tracks need to be copied to R2, it will NOT keep holding the tracks in cache to be moved over to R2).

regards,

Saurabh Rohilla

anoopcr
3 Argentum

Re: What will happen to SRDF/A delta set after the session drop due to max WP

Hi Saurabh,

So during normal operation,Will delta set create any invalids.Just want to understand how the delta set pushing data to R2 symm

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sauravrohilla
4 Tellurium

Re: What will happen to SRDF/A delta set after the session drop due to max WP

HI Anoop,

Will delta set create any invalid?? I am not too sure about the question. To understand how delta set pushes the data to R2, you can look at the SRDF product guide. In a nutshell, SRDF/A works in Cycle.

1) Capture

2) Transmit

3) Recieve

4) Apply

Lets assume your minimum cycle time is 30 sec, so R1 symm will start capturing the data for 30 sec and then do a cycle switching (Capture cycle becomes transmit and tranmit becomes Capture). Once the data reaches to transmit, it starts sending it over the RDF link to R2 Symm where it is received in Receive cycle, again after 30 sec, cycle switching happens (receive cycle becomes apply and apply becomes receive) and whatever data in Apply cycle is destaged to the disk.

There is more to it which you can find in Product guide. Please ignore if you already know it.

regards,

Saurabh

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anoopcr
3 Argentum

Re: What will happen to SRDF/A delta set after the session drop due to max WP

Thanks Saurabh

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