ahmad_faraz
2 Bronze

difference between copy on access and precopy with differential in timefinder clone

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what is the difference between  between  copy on access and precopy with differential in timefinder clone

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Fenglin1
4 Beryllium

Re: difference between copy on access and precopy with differential in timefinder clone

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Copy on Access resolve the problem in the scnario when data is copying during TF/Clone is active, but Host need to access the track which has not been copied. Copy on Access will copy the track first to the target

Precopy enables the background copy during TF/Clone creation

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eliyaz1
1 Copper

Re: difference between copy on access and precopy with differential in timefinder clone

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With the CopyOnAccess, actual copying of the data is deferred until either tracks on the source device are written to or tracks on the target device are read or written.  i.e. after activating the copy session, only those tracks that have been written to the source or written/read from the target will be copied to the target device

Precopy option starts copying tracks in the background as soon as the session is created, i.e. before activation.

A differential  clone operation copies only those device tracks that have changed since the initial full clone was performed.

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ahmad_faraz
2 Bronze

Re: difference between copy on access and precopy with differential in timefinder clone

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As far i understand i can use precopy with differential to get the increamental dat since last clone was formed

For which situation copy on access  will be used .Will it give me incremental data  once is recreate the session .

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Fenglin1
4 Beryllium

Re: difference between copy on access and precopy with differential in timefinder clone

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Copy on Access resolve the problem in the scnario when data is copying during TF/Clone is active, but Host need to access the track which has not been copied. Copy on Access will copy the track first to the target

Precopy enables the background copy during TF/Clone creation

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ahmad_faraz
2 Bronze

Re: difference between copy on access and precopy with differential in timefinder clone

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Ok ...

Suppose i have copy on access session ...and when i activate the session ...it will copy the tracks till the point of activation .

So if again  session is created  ,next time when i active  will it take differential data ....or the data from where we have activated again .And yes will it overwrite the clone copy or  differentially copy data  on clone copy.

thanks

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dynamox
6 Thallium

Re: difference between copy on access and precopy with differential in timefinder clone

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ahmad.faraz@hp.com wrote:

Ok ...

Suppose i have copy on access session ...and when i activate the session ...it will copy the tracks till the point of activation .

nothing is copied in the background, data only gets copied when it's either written to from source or read from target. If you want data to be copied to target, you need to use -precopy and if you want to be able to re-create the session to capture incremental changes you need to use -differential with -precopy

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ahmad_faraz
2 Bronze

Re: difference between copy on access and precopy with differential in timefinder clone

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so as i understand ,

if I have backup  to disk happening  from the clone with copy on access session activated  ,as along  data is being read from the clone data  will be pulled from the source to target as the blocks are being accessed from target .

So if i terminate and activate  the session again after 2 hours the i will  get the whole data again ...hence no differentilal

can some put more light on this ,would be much appretiated

Faraz

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dynamox
6 Thallium

Re: difference between copy on access and precopy with differential in timefinder clone

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if you terminate your clone session regardless of what parameters you used, everything begins from scratch. Here are a couple of notes from SE TImefinder guide

Fully copying to a clone


Starting with Solutions Enabler version 7.0.0.370, the –copy option is specified by

default. When the copy session is activated, data begins background copying so that a

full copy of the data will become available on the target device. While background

copying, the state of the device pair is CopyInProgress; when the operation

completes, the state goes to Copied. The copy session must be activated before the

target host can access the data. However, once the session is activated, the data is

available immediately to the target host.

Creating a session in nocopy mode


To create a copy session without a full background copy, you must use the -nocopy

option. When activating a copy session in nocopy mode, the default device pair state

is CopyOnAccess. This means that after activating the copy session, only those tracks

that have been written to the source or written/read from the target will be copied to

the target device. A full data copy to the target device will not occur unless all of the

device tracks are accessed or written to while participating in the active session.

Note: If a write occurs to the source device, old data is copied to the target device. If a write

occurs to the target device, new data is written to the target device.

When Enginuity detects that a source-protected track was written, it c

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