SQL Server Admin 2014 :: High Number Of VLFs
Oct 7, 2015
I have heard that high numbers of VLF's aren't good. It can impact performance and can delay recovery time, so I wanted to test that.
I created 2 DBs with 100MB datafile and 50MB logfile.
TestDB log file had 100MB autogrowth
TestDB2 log file had 1% growth.
I inserted 1048576 records, took the backup
Ran DBCC loginfo and
TestDB had 40 VLFs and
TestDB2 had 165 VLFs
But when I restored both DBs, this is what I got.
TestDB:
RESTORE DATABASE successfully processed 42258 pages in 4.420 seconds (74.691 MB/sec).
SQL Server Execution times:
CPU Time = 125ms, elapsed time = 8323 ms.
TestDB2:
RESTORE DATABASE successfully processed 42257 pages in 3.943 seconds (83.724 MB/sec).
SQL Server Execution Times:
CPU time = 109 ms, elapsed time = 8314 ms.
Question is: Where is the difference? How TestDB which has 40 VLFs are better than TestDB22 which has 165 VLFs.
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Aug 18, 2015
I am trying to create a job that runs against my High Availability listener server.
It is a fairly simple SQL statement in the job - execute tsql.
When I try and run the job I get the error:
Executed as user: NT SERVICESQLAgent$SQL2014A. The target database ('BB_Prod') is in an availability group and is currently accessible for connections when the application intent is set to read only. For more information about application intent, see SQL Server Books Online. [SQLSTATE 42000] (Error 978). The step failed.
I thought there was a way to run a select statement as a job against the listener? The tsql step is only a select.
Is there a way to pass in the application intent = readonly as part of my SQL statement?
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Mar 5, 2014
My database server memory utilisation is growing faster from past 1 week. it remained same for 1 week around 55% and now it is going to 70% and increasing.
Total OS memory is 32GB and I kept cap for sql server memory upto 29GB. Dont know what to do..
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Jul 9, 2015
I have a situation where I need to rebuild indexes on a large DB (500G).
When I do a test run of the rebuilds in my test environment it uses 100G of space - which is fine with me.
When I do a rebuild in my High Availability environment - same DB, same script - it eats up over 600G of space and fills the volume.
What can I do without removing my DB from H/A to rebuild the indexes?
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Nov 3, 2015
We are looking at going down the High Availability Always On route. However we have some concerns around the lack of support for MSDTC. In short we are concerned that developers may introduce functionality either on purpose or by mistake that uses the or escalates the Query’s to the MSTDTC. As this could result in database splitting.
Understand that this will be a moot point in SQL 2016 but for 20122014 is it possible to disable the MSDTC to protect against this and run High Availability Always On. ? Does it just need to be disabled on the SQL Server or does it need to be done on the application server ?
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Apr 7, 2015
I have this query
SELECT top 100 Ltrim([text]),objectid,total_rows,total_logical_reads , execution_count
FROM sys.dm_exec_query_stats AS a
CROSS APPLY sys.dm_exec_sql_text(a.sql_handle) AS b
where last_execution_time >= '2015-04-07 10:01:01.01'
ORDER BY execution_count DESC
But the result of execution count is from the first. I want to know it only one day.
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Jun 2, 2014
I am writing a performance baseline test.
The first test writes 5000000 rows in one table. I realise this is not representative OLTP behaviour, but it worked me to start interpreting performance counters and to test several setups to be discussed with our server, storage and network administrators. This way we have been able to compare the results of different hard disks, Lun vs vmdk, 1GB vs 10GB network, AMD vs Intel, etc. This way I can also compare several SQL setups (recovery model, max memory config, ...)
The screenshot shows the results of 2 runs on the same server : Win2012R2, SQL2014, 16GB RAM.
In test 1 min/max server memory was set to 9215MB/10751MB
In test 2 min/max server memory was set to 13311MB/14847MB
The script assures the number of bytes inserted in the nvarchar columns is always the same.
This explains why the number of pages and the number of MB in the table are the same at the end of the 2 tests (column 5 and 6)
Since ca 13GB has to be written, the results of test 1 show the lead time is increasing once more than 10GB has been inserted (column 8 and 9) In addition you can see at that moment
- buffer cache hit ratio is decreasing
- page life expectance becomes "terrible"
- free list stall/sec increases
- lazy writes/sec increases
- readlatency increases (write latency does not)
In test 2 (id 3 in column 1 in the screenshot) those counters are not really influenced (since the 5000000 rows can all be stored in memory).
Now what I do not understand is :
Why the number of pages read (instance level) as well as the number of bytes read and the number of reads (databaselevel) is increasing extremely during run 1.
I expected to see serious impact on write behavior, since SQL server is forced to start flushing dirty pages once memory is filled. Well actually you can see here the number of writes (not the the number of bytes written) starts to increase faster in test 1 after 4000000 rows, but there's no real impact on write latency.
Finally I want to notice
- I'm the only user on this machine
- the table has a clustered index on a identity column
- there are no foreign key constraints
- inserts are executed using a loop, not one big transaction
- to monitor progress and behaviour/impact, each 10.000 loops the counters are stored using dmv queries
So I wonder why SQL Server starts to execute so many reads in test 1.
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Feb 2, 2015
Database File Placement Layout? We are planning to implement a new SQL Server 2014 OLTP Database with a 1 TB Data file and 1 TB Log File. I am looking at the possible layout of the database files and trying to determine the best possible configuration. My knowledge/research tells me that items which need separate storage due to constant simultaneous access are:
Data files – should go on the fastest reading storage.
Log files – should go on the fastest writing storage.
TempDb – involves a lot of writing at the same time the data files are being read.
Indexes - (including full text indexes) - involves a lot of writing at the same time the data files are being read.
Also, are there any benefit to having multiple OLTP Database Log files? Because SQL Server writes to the log file sequentially, I do not see any advantages to having multiple database log files. In a SQL Server 2012 Class I took last summer, under “Determining File Placement and Number of Files”, it states “Use a single log file in most situations as log files are written sequentially.”
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Sep 9, 2015
Our development team wanted to create a database user for each application user in the application and use these for granular data access control, which at first, sounded like a good idea but our initial testing ran into some interesting results.
Our target user base was about 15 million users with an estimated 1% concurrency rate, and finding no MS documentation on an upper limit to the number of users a database can have we began some load testing to see how the database performed. In the hundreds of thousands of users range our test database had a hard time performing well under light loads (even without any concurrent connections).
When we purged the users and reverted back to just a handful of service accounts, performance went back to "normal" under the same loads. I began to wonder if this is a situation where throwing more hardware at the problem would overcome the issue or if there is a practical upper limit to the number of users a single database can handle well.
(There were of course other cons to this arrangement and I certainly was never going to expand the users tree in the object explorer for a database like this, but we thought it a solution worth investigating.)
What is the largest number of users any of you have had in a single database?
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Oct 27, 2015
I have a 2 node cluster having 4 cores each wherein having 3 instances of SQL 2008 R2 enterprise comprising of 60 databases, 20 on each instance. I need to setup mirroring for each of the databases to a secondary server having 4 cores and 3 instances. What i understand is that in this case the mirror server will be providing max of 512 worker threads and the 60 mirror databases would consume 240 threads.what all needs to be checked for looking into the feasabilty of going ahead with a async mirror setup as mentioned above.
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Nov 6, 2015
I've installed the MDW (Mangement Data Warehouse) database on our central monitoring SQL Server. I've then added a number of servers to be monitored. The data is collected on the servers that are being monitored and uploaded to the central MDW Monitoring server.
On the servers that are being monitored, I'm seeing a large number (over 1000) of SPIDs being generated by 'SQL Server Data Collector'.
Is this normal behaviour? I've seen more blocking as a result of this.
Is there any way to reduce the number of SPIDs generated?
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Apr 3, 2015
Basically the question is, which number should I pick?
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May 3, 2015
ID A B C AVG
------------------------
1 08 09 10 -
------------------------
2 10 25 26 -
------------------------
3 09 15 16 -
------------------------
I want to calculate the average of the larges two number from the column A,B & C for particular identity and store that average in the AVG column....
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Aug 27, 2015
I want to set up a database role so that users can use sp_readerrorlog through SSMS. It does a check on membership in the securityadmin role.
I have tested it and can see you can grant execute on xp_readerrorlog but the SSMS GUI uses sp_readerrorlog.
I thought I could create a user/certificate and add the signature to sp_readerrorlog but it's not permitted (likely because it's not a normal database object).
So the other solution is to add the users to the securityadmin role but then explicitly deny alter any login (best done with a custom server role in 2012+ but otherwise just manually in 2008). I tested this out and it works, I'm not able to alter any logins or increase my own permissions, I also did a check of what's reported from fn_my_permissions(null, null) and it shows minimal permissions like I'd expect.
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Apr 14, 2015
I inherited a lot of Servers to upgrade to 2014 to include an SSRS Server.
The encryption Key was never backed up and it seems that no one knows what the password is?
Do I have to manually load the reports? There are a lot of Reports.
[URL]
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Sep 26, 2013
I want to use BCP to load data from a text file.
By default, constraints are turned off in bcp, so I use the CHECK_CONSTRAINTS hint.
bcp aborts if ANY of the rows contains a FK violation. No data get loaded.
So if I add the -b 1 batch size option, it loads all data UNTIL the first FK violation, but nothing after that.
I want to load EVERYTHING ... except for the violations. But bcp won't let me. Is there a way?
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Jan 13, 2014
If I install an instance with Windows Only authentication, and then change it to Mixed Mode, if I enable the sa login, the password has already been set. What is the default? If it's generated, how secure is it? Is the password generated? What algorithm is used for that?
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Mar 21, 2014
My sql databases in SQL Server 2014 has the status "suspend" as I saw in SQL Management Studio. I can't restore to serviceable condition sql databases through standard procedures. I need to restore .mdf file.
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Jun 18, 2014
I am using a monitoring system where I can monitor a numeric SQL result assuming the result is one field and one row.I would like to do this to say monitor the free available space or percentage on say the Master database. DBCC SQLPERF gives me a few columns and results for all databases on the server.
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Jun 25, 2014
In our environment applications are using a DNS name which points to the physical server ip address. Now we are planning to move to 2014. We are planning to have servers in different subnets so we will be having two ip adresses for listener. How we can point the DNS to the listener ips? If failover happens can the DNS point to the exact ip address of the listener where it's primary node?
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Jul 31, 2014
Is there a way to schedule a sql job to run at different intervals
For eg:
The job should run at
7:00 Am
8:00 AM
and then at 10:00 Am
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Nov 19, 2014
We installed the Sql 2014 in Test server.
We observed frequently
"Process 0:0:0 (0x1e10) Worker 0x00000006B6D341A0 appears to be non-yielding on Scheduler 13. Thread creation time: 12906028806348. Approx Thread CPU Used: kernel 0 ms, user 0 ms. Process Utilization 13%. System Idle 84%. Interval: 70189 ms."
Is it better to run the profiler or performan counter?
What are the filters we have to select in the profiler to monitor the Sql server
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Dec 8, 2014
I have a SQL server box running 2014 reporting services. I have another server running IIS v8.
I would like to be able to connect to the IIS site and be given the SSRS report browser.
So externally if I browse to [URL], I am presented with the report server interface, the same as if I browse to http://xxx.xxx.xxx.xxx/reports internally.
What are my options?
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Dec 11, 2014
What is the best approach for a read only copy of a database that is ~ 1TB. The primary database is fed nightly with an ETL process. We are currently trying to duplicate the ETL to read only server but that process is not going well. So we are looking at other options to let SQL make the copy.
The primary database is on a Win12R2 with SQL 12 or 14, a 2 node A/P failover cluster.
The read only copy will be on a Win12R2 with SQL 12 or 14. It is not a requirement to fail over to the read only copy if the primary should go down.
What would best the approach to accomplish the end result?
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Jan 12, 2015
I did not worked on AVG in sql 2012, what are the possible errors and how to resolve in always on in sql 2012 .
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Jan 18, 2015
I have 10 databases which are configured as principal in mirroring I need to failover all the databases as part of failover , instead of writing query each database as parner failover, is an script which will generate the databases as principal to failover ?
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Feb 18, 2015
How to check the delay in between replicas in AG?
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Feb 26, 2015
my 4 GB .OST file is corrupted and i am not able to access my mails and contacts.
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Apr 7, 2015
I got query from sysproccesses and the result for one spid is : SQLAgent - TSQL JobStep (Job 0xF3BDA6DFF9DCF94D81FF97C49EDA7C61 : Step 1
Which job has this code : 0xF3BDA6DFF9DCF94D81FF97C49EDA7C61
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May 28, 2015
After installing SSMS on some computers - the only way we can get SSMS to run correctly is to run it as the administrator. Is there a way where you don't have to do that? These end users are logging as themselves and have accounts in SQL Server all set up - but SSMS will only launch for them if we right click and select "run as administrator".After doing some digging - it seems that this is a common problem out there.
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Jun 19, 2015
Have a SQL 2014 install and cannot for the life of me get the maintenance plan to remove old backups. I've tried everything. Rights to the folder where the backups are stored are adequate, extension set in the clean up task is as it should be, etc. Log shows the job ran successfully. Running the command manually shows successful completion, but backups are still not removed.
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Jul 29, 2015
when execute the restore log command, in the messages window it shows how many seconds the restore takes, at the meantime, on the status bar, it also shows the seconds the command takes.
Two values are different and could be very different, please see below examples , restoring takes 1.8 seconds, but in total the command takes 4 seconds to complete, the other one is 8.1 seconds and 12 seconds.
What does SQL Server or Windows do after the restoring?
pic a:
pic b:
I did a xperf, I can see after the restoring is completed, sql server did garbage collect and log write, which just run very quickly, but storage is busy on reading the log file for nearly 2.2 seconds( 4-1.8), and 4 seconds ( 12-8.1) .
pic 1:
pic 2:
see pic 1 above, from 13 to 17, the restore operation is finished, but the storage jump to 100% active to do some reads, only reads no writes. zoom that period shows pic 2, it read 4096 (I don't know the unit size) for about 4 seconds, what does this do?
Data file, log file, backup file are no different drives, but all local drive, the interesting point is the read jumped after restoring, I tested it on different server, same result...
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Aug 9, 2015
I've got an old version of SQL Server 2008 R2 Developer Edition on an old PC which is failing. I've got a new PC and have put SQL Server 2014 Developer Edition onto it. Now before the old machine completely dies, I've gotten into SSMS on the old machine and did a backup of the databases I want to save. I've moved the .BAK files to where I could get to them from SSMS on the new machine. I've gotten into SSMS and tried to do a restore the database to my new machine. However I'm getting an error that does not make any sense to me.
The database I'm I've backed up is named JobSearch. When I backed it up, that was the only database I had selected. Like I said I copied the .BAK to the new machine. Got into SSMS, told it that I wanted to restore the JobSearch database, telling it where I wanted to put it, and it then immediately fails with a:
"Restore of database 'JobSearch' failed. System.Data.SqlClient.SqlError: Logical file 'VideoLibrary_Data' is not part of the database 'JobSearch'. Use RESTORE FILEISTONLY to list the logical file names."
Well of course VideoLibrary isn't "the logical file". But neither did I select VideoLibrary (which is a database I also want to move, but I'm doing one at a time). So what in heck is going on here? Why is it complaining about a database I haven't even selected to back up? Why, when I check everything on the old machine, it's backing up JobSearch, but on the new machine it sees VideoLibrary?
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