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Monitor : Transaction Log Free Space (%) SQL 2016

Question
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The Transaction Log Free Space (%) is not working. The SQL 2016 Management Pack version is 7.0.7.0, the MP guide clearly says that - "Fixed issue: the "Transaction Log Free Space (%)" monitor does not work"
For one of our DB I changed the Threshold to 100% and Sample count to 1. The default Threshold is 10% and Sample Count 6.
Another query is - How does this monitor work, Is it running as a script or capturing any performance counter ?
Also, there are product knowledge says - there is different settings for Auto Growth and No Auto Growth options.
Is there any alternative ways to monitor the transaction log files.
Need a serious help for this issue.
Amanpreet Singh Bansal
Tuesday, February 26, 2019 2:34 AM
All replies
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Hi,
the monitor uses a Performance Counter to collect the data:
Microsoft.SQLServer.Windows.Monitor.Database.TransactionLogSpaceFreePercent (UnitMonitor)
By default this monitor is not enabled. Did you enable (overwrite) it for your SQL servers?
You mentioned "For one of our DB I changed the Threshold to 100% and Sample count to 1. The default Threshold is 10% and Sample Count 6." but this would not be correct if you want to produce alert, because it is a % Free Disks Space, so if you want to test you need to test with small numbers, like 1 or 2%. 100% Free Disks space would be the opposite - you have no problems with space.
About Autogrow: Yes, autogrow and the related settings affects of course the Free Space of the transaction log, so it should be also considered when configuring the monitor.
Hope I could clarify this. Regards,
(Please take a moment to "Vote as Helpful" and/or "Mark as Answer" where applicable. This helps the community, keeps the forums tidy, and recognizes useful contributions. Thanks!) Blog: https://blog.pohn.ch/ Twitter: @StoyanChalakov
Tuesday, February 26, 2019 9:16 AM -
Hello Stoyan
I did see the alert after making the threshold to 100% as this is free space available and I wanted to alert if 100% logs are free.
Transaction Log Free Space (%) of the database "XXXX" in SQL instance "XXXX" on computer "XXXX.XXX.XXX.XXX" is too low. See "alert context" tab for more details. Space available: 98.9357896741691%.
The graph also shows when ever the log touches 100% free we are getting the alert.
I have now changed the Th to 10% and Number of sample 10 to 1 only.
I wanted to know if this monitor check the same results as checked by below query :
DBCC SQLPERF(LOGSPACE);
GO
Database Name Log Size (MB) Log Space Used (%) Status
------------- ------------- ------------------ -----------
master 3.99219 14.3469 0
tempdb 1.99219 1.64216 0
model 1.0 12.7953 0
msdb 3.99219 17.0132 0
AdventureWorks 19.554688 17.748701 0
If not do we have any ways to check it, may be any community management pack or custom monitor.
Amanpreet Singh Bansal
- Edited by Aman Bansal Saturday, March 2, 2019 10:32 AM
Saturday, March 2, 2019 10:30 AM -
It's hard to say how the monitor gets the result because it relies on a custom dll , which we would have to decompile to see exactly what it's doing.Saturday, March 2, 2019 3:29 PM