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difference between copy on access and precopy with differential in timefinder clone
what is the difference between between copy on access and precopy with differential in timefinder clone
This post is more than 5 years old
22 Posts
0
3494
what is the difference between between copy on access and precopy with differential in timefinder clone
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Fenglin1
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2.1K Posts
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March 20th, 2012 03:00
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
eliyaz1
6 Posts
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March 12th, 2012 10:00
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.
ahmad_faraz
22 Posts
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March 19th, 2012 23:00
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 .
ahmad_faraz
22 Posts
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May 16th, 2012 23:00
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
ahmad_faraz
22 Posts
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May 17th, 2012 05:00
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
dynamox
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May 17th, 2012 05:00
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
dynamox
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May 17th, 2012 06:00
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