change in lsn behavior between 9.7 and 11.1

Harishkumar .Pathangay

change in lsn behavior between 9.7 and 11.1

Hi all,

Have they changed behavior of LSN in 11.1 and later releases. it is beyond extending the range of LSN values from 6 bit to 16 bit. The way in which the LSN is consumed is itself a little bit different.

In 9.7, if I import one record with 1MB blob object, it consumes 1MB of LSN Space - the hexadecimal for 1MB, even though it is a single record.

In 11.1, if I import the same record [1 MB blob object], it consumes only 62 LSN hexadecimal, but LSO will be of 1MB.

Also, connect/disconnect recycles without explicit activation of database is not consuming LSN values.

these are significant changes, but I am not able to find any documentation in info center highlighting such changes.

my test cases definitely are valid, I did like 10 times with same results.

Any Help on that ? I am thinking the way in which the LSN are consumed is drastically changed between releases 9.7 and 11.1. Any documentation pointing to that for assertion will be of great help. 

thanks,

Harish Pathangay

Harishkumar .Pathangay

RE: change in lsn behavior between 9.7 and 11.1
(in response to Harishkumar .Pathangay)

Hi,

Please find a table with demonstration and numbers to corroborate my point.

Any Explanations on behaviour of LSN is of great help.

Thanks, Harish P

Attachments

  • DB2-TnT-134-LSN.png (67.7k)

Harishkumar .Pathangay

RE: change in lsn behavior between 9.7 and 11.1
(in response to Harishkumar .Pathangay)

Hi,

Is LSN a measure of space or number of log records? or a combination of both. I did some test cases and you can find that it is version dependent. It behaves as a measure of space in 9.7. It behaves as a combination of both space and number of log records in 11.1.3.3. Also, you will not loose LSN space because of frequent connect/disconnect cycles. please look at the following thread for more information. https://lnkd.in/fTYV9GA i am also attaching the test cases i did. Any Inputs will be helpful.

Jeff Goss

RE: change in lsn behavior between 9.7 and 11.1
(in response to Harishkumar .Pathangay)

Yes, starting in version 9.8 for pureScale and 10.1 the LSNs switched from being essentially an offset into the log stream and now just increase monotonically.  The LSO is now the offset. 

Harishkumar .Pathangay

RE: change in lsn behavior between 9.7 and 11.1
(in response to Jeff Goss)

Hi All,

Please consider this thread closed.

thanks,

harish p