Mode 0 block level copy

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Mode 0 block level copy

Postby rexwithers on Tue Oct 09, 2018 11:20 pm

You have said for the new Mode 0 block level copy:

"Destination files must not be modified by any other profile, person, or tool"

Can you give a little more detail and expand on whats meant by that (perhaps a little detail on how it work so that I understand the why and make sure I don't break things).

My situation is that I backup Hyper-V VHD's that backup to an external HDD, I have this same setup replicated for multiple customers on multiple sites.
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Re: Mode 0 block level copy

Postby superflexible on Wed Oct 10, 2018 1:53 am

Hello,
this only means that nobody should use the VHDs on the external HD. Because if somebody opens them there and modifies them, then Syncovery won't know which blocks are different any more.

In mode 0, Syncovery divides the file into small blocks of a certain size, and remembers each block's MD5 checksum in a local database file. When it is run again, it re-reads the whole file and calculates the checksums again and copies only the modified blocks. So the destination file should not be touched by any other software.

When copying locally, this mechanism may save some USB bandwidth but may not actually make the whole process faster, because the complete source file needs to be read and MD5 checksums need to be calculated.

To get more speed, you can use the new File System Monitoring Service in Syncovery 8. It will record a list of changed blocks during the day and when Syncovery makes the copy, it will immediately know which blocks need to be copied, rather than having to scan the whole source file.
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Re: Mode 0 block level copy

Postby rexwithers on Wed Oct 10, 2018 10:04 pm

Can I use $WEEKDAY as a target when using "Mode 0: With File System Monitoring Service (new in Syncovery 8)"

The software allows it but I'm not sure how the program would know which changed parts to add to which $WEEKDAY ?

I assume Mode 1: With Database would work with a $WEEKDAY target because it would store the correct information the the database?
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Re: Mode 0 block level copy

Postby superflexible on Sat Oct 13, 2018 6:12 pm

Hello,

mode 0 with the file system monitoring service can tolerate varying destinations, i.e. you can use the $WEEKDAY variable.

mode 1 with database cannot, because it doesn't store the checksums for so many different destination in the DB.
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