Transaction Log Size

Hello Everyone,

Is there anyone realize Solarwinds and Microsoft are calculating the transaction log size different on the database ?

We are checking transaction log size with dbcc-sqlperf it's giving us a value. After that we are checking over Solarwinds but the result is not the same.

https://docs.microsoft.com/en-us/sql/t-sql/database-console-commands/dbcc-sqlperf-transact-sql?view=sql-server-ver15

Both of them is trying to calculate the same thing but result is different. Is there anyone find a solution or workaround for this ?

We already talked with support and Dev team but they are saying it's correct value.

Thank you.

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Your_Daddy

How did the support and Dev team verify the correct value?

Seashore

If you go to the SQL server and look at the actual log file itself, how big is it? Who is right? Is it off a lot?

idriskerti

Here is the answer that I got from the Dev Team :

Hi, the differences is - dbcc sqlperf has own log file that collects all transaction operations. It calculate log size and percentage based on database size that was calculated by a SQL ( it include system tables, system data, other data that was generated with a database creation + additional precedures and scripts) in other words full database size. This solution shows us only size of log file and percentage from the whole db size, but this db size could include database files, stored data etc. ( we dont see db size amount value, only percentage).

Our procedure do a calculations of database size based on a data size that we have collected in another tables, so we manually collect size of our database by stored data in it. Then we have both values, log file size and db data size. There are other ways to get db size ( [Display data & log space info for a database - SQL Server | Microsoft Docs|https://docs.microsoft.com/en-us/sql/relational-databases/databases/display-data-and-log-space-information-for-a-database?view=sql-server-ver15] ), i think each of this will return different values and our percentage will be different. as log file size always the same, but database size different based on a method we use to collect the data

Orion and Microsoft calculating the trancation log size with different databases.

idriskerti

Here is the answer that I got from the Dev Team :

Orion and Microsoft calculating the trancation log size with different databases.

KMSigma.SWI

The dbcc-sqlperf command will give you a "right now" number. Where are you seeing the other number in a SolarWinds product?

idriskerti

We are seeing on the Appinsight for SQL Application Details Page.

Dev Team also shared the calculation of the formula. The calculation formula is

TransactionLogFreeSpace * 100 / (TransactionLogSize + TransactionLogFreeSpace) AS TransactionLogFreeSpaceInPercents,

KMSigma.SWI

So what we're reporting in SAM is Transaction log free space based on the transaction log size - not the disk size. And we're doing it on a routine basis (the last poll).

How far off are the numbers between the two entries? On a highly transactional database (like the SolarWindsOrion one or other OLTP databases), I can see this number varying greatly due to log write fluctuations.