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I have a strange situation and I would like to get someone else taught.

I have a database that have 2 log files (I know, it should not and I plan of fixing it soon).

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Now for what I know, log file are written sequentially (filling up one VLF then the next one) so I would expect the log file with the active VLF to fill up until it "round rubbin" into the next one but this is now what I observed.

Here's the log file usage at my first check:

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The fact that both were used at the same percentage is the reason why I checked again a couple of minute later:

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Why does both log file fill at the same time ?

I checked and there is no strange trace flag enable on that instance that would explain it.

Thank you for your help.

Dominique Boucher
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  • Yikes! Your evidence is sure compelling. But luminaries like Brent Ozar, Paul Randal, Pinal Dave, and Aaron Bertrand have all written that log files get written to sequentially. Here are some links. I'm combing through them to see if I can find the reason your case seems contrary to all of their expertise. https://www.brentozar.com/blitz/multiple-log-files-same-drive/ https://www.sqlskills.com/blogs/paul/multiple-log-files-and-why-theyre-bad/ https://blog.sqlauthority.com/2020/04/11/sql-server-multiple-log-files-to-your-databases-not-needed/ https://dba.stackexchange.com/a/62348/170408 – Doug Deden Feb 08 '22 at 19:56
  • Can you use DBCC LOGINFO to see if it indicates the same "parallel" behavior? See https://dba.stackexchange.com/a/62353/170408 for an example. – Doug Deden Feb 08 '22 at 19:59
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    Thanks Doug, that's a good idea ! I checked and it seems like only one VLF is active (as expected)... I don't see anything else in the results that could help me more... I'll double check the request I use to get the file usage as it, in theory, doesn't make any sense – Dominique Boucher Feb 09 '22 at 13:40

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