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Timefinder Clone - VMAX
Hi guys,
In a timefinder clone relationship once after the pairs are activated and 100% copied state, how it tracks the changed tracks in source and target devices? where we can look for the info? Is it the modified track displayed when we hit the query command?
I vaguely remember the changes in tracks between source and target devs of timefinder Clone are tracked in a bitmap file, is it right? if so will there be performance impact if the changes in tracks differ by a big margin? I understand the recreate will have big delta set to be copied to target devs and other than that will there be any other impact?
Thanks
PedalHarder
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June 30th, 2016 23:00
You may need to enable the SYMAPI_TF_COUNT_MODIFIED_TRACKS parameter in the options file to see the deltas in the query output.
itzzdp
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July 1st, 2016 10:00
Thanks Jasonc.
Yes all the time I see modified tracks count sticks to 0. I will check for a document which gives more info on enabling the option.
2nd question: once activated and 100% copied source and target are independent devices with their own data. So modifying the tracks on both source and target and increase in the count of modifying tracks will it occupy more space on cache or where this tracking info will be stored. Will it have any impact on performance by any chance?
PedalHarder
465 Posts
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July 4th, 2016 16:00
There is no additional overhead in monitoring the modified tracks or additional cache required after the copy is complete, nor performance overhead. As you say, they are effectively independent devices (copy on first write is no longer going to occur).
The (replication) cache allocation is done at the point that the source <> target relationship is created. It is returned after the terminate completes.
itzzdp
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July 5th, 2016 08:00
Thanks a lot.