yaribhas
2 Iron

SRDF/A question

In a normal case of SRDF/A how can we know that our R2 data is a valid one?

I know bringing the host up on the DR site is an option but is there any other way to find out?

In symrdf -g ** query -rdfa output I see the below

RDFA Session Number                : 9
RDFA Cycle Number                  : 202
RDFA Session Status                : Active
RDFA Consistency Exempt Devices    : No
Write Pacing Exempt Devices        : No
RDFA Minimum Cycle Time            : 00:00:45
RDFA Avg Cycle Time                : 00:02:55
Duration of Last cycle             : 00:03:59
RDFA Session Priority              : 33
Tracks not Committed to the R2 Side: 394995
Time that R2 is behind R1          : 00:04:02
R2 Image Capture Time              : Tue Jul 19 09:13:57 2011
R2 Data is Consistent              : False
RDFA R1 Side Percent Cache In Use  : 33
RDFA R2 Side Percent Cache In Use  : 18
R1 Side DSE Used Tracks            : 0
R2 Side DSE Used Tracks            : 0
R1 Side Shared Tracks              : 0
Transmit Idle Time                 : 00:00:00

What do the items in bold mean? If R2 data is consistent parameter is FALSE, then does it mean that we do not have a legit R2 data yet?

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5 Replies

Re: SRDF/A question

Looks like you still have a lot of data left to sync:

Tracks not Committed to the R2 Side: 394995

That tells me that you still have close to 400K outstanding tracks to send over at the time you ran the command.

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yaribhas
2 Iron

Re: SRDF/A question

Yes we have more than 1TB left to copy but I need the understand what the items in bold mean?

If we were to finish the copy one time and the links were suspended for some reason and we went back to some number of invalids left to copy, would we have legit copy on the R2 side? Meaning will we be able to bring the DR server up? I know we would not have the data on R2 that still needs to be copied but what ever we have copied already would be legit correct?

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huazhihui
1 Copper

Re: SRDF/A question

When "R2 Data is Consistent"  item is set as True, then the R2 data is a restartable copy of data. It doesn't mean the R2 data is exact the same as R1, it has some time delay as R1. ( in SRDF/A environmen, normally, R2 will have two cycle delay comparing to R1, the cycle time is normally 30s, but it will be extended considering the IO transferred between R1 and R2 )

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yaribhas
2 Iron

Re: SRDF/A question

That is good information. Thanks. I have one more question.

Would the "R2 data is consistant" item be set to TRUE when we go to "0" invalid tracks?

I am asking this question because we were down to "0" and went back up in invalid tracks and we still have the bit as FALSE.

Does SRDF/A have to complete multiple cycles before that bit is set to TRUE?

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huazhihui
1 Copper

Re: SRDF/A question

You  need to enable the consistenc for the srdf/a group even if the invalid tracks becomes zero on the link.

The following is what I copied from EMC® Solutions Enabler Symmetrix® SRDF® Family CLI Version 7.1.1 page 41, just for reference.

The enable action enables consistency protection for devices in SRDF/Asynchronous

mode by device group or device list. If data cannot be copied from the R1 to the R2,

all devices in the group will be made Not Ready on the links to preserve R2 data

consistency.

To enable consistency protection for SRDF/A pairs in device group

prod, enter:

symrdf -g prod enable

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