Gaps in historian data after moving history blocks between servers

If you zoom into a shorter period including one of the "gaps", does the gap remain or get filled in? Check with a period of 12 hours or less.

Hi Elliot,

gap is still there when zooming in

Some more questions:

1. Just eyeballing the chart, it looks like the gaps and the filled portions are about the same duration and might be 24-hours each. If so, this suggests there might be something wrong with alternating history blocks (duplicates, overlapping, etc.).
2. Does the same gap pattern align with other tags (e.g. several tags have 12-minute gaps for the same period)?
3. Is some application/script routinely updating metadata for the tags (e.g. TrendHi/Lo, description, etc.)?
4. If so, is there any correlation with those metadata changes? You might be able to tell using a query like this: select * from TagHistory where TagName = 'Foo'

If none of the above leads you to a resolution, I suggest reaching out to Tech Support and include specific version information about the Historian version (old and new if this is related to an upgrade). 

Some more questions:

1. Just eyeballing the chart, it looks like the gaps and the filled portions are about the same duration and might be 24-hours each. If so, this suggests there might be something wrong with alternating history blocks (duplicates, overlapping, etc.).
2. Does the same gap pattern align with other tags (e.g. several tags have 12-minute gaps for the same period)?
3. Is some application/script routinely updating metadata for the tags (e.g. TrendHi/Lo, description, etc.)?
4. If so, is there any correlation with those metadata changes? You might be able to tell using a query like this: select * from TagHistory where TagName = 'Foo'

If none of the above leads you to a resolution, I suggest reaching out to Tech Support and include specific version information about the Historian version (old and new if this is related to an upgrade). 

Hi Elliot, the gaps were exactly one block (24hrs)  and allt tags were corrupted and aligned. item 3 - no

I dont know what was causing this but i ended up moving all blocks from the circular folder, dropping the database and creating new one, paste all blocks at same time (few years of data) and then no gaps.  In my first example, i copied them in smaller increments, and the first month was fine but next batch of one year had the gaps.  I have no idea why this happened, but this is not the first time I get gaps randomly.

one more thing,  the approach i was using was exactly this: 

https://softwareforums.aveva.com/heroes-hq/f/aveva-historian/83230/is-it-possible-to-combine-history-data-history-blocks-of-2-historians-with-the-same-set-of-tags-to-1-historian-server-without-tiered-setup