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 SQL Server Administration (2000)
 Memory Usage & Refused Connections

Author  Topic 

martinch
Starting Member

35 Posts

Posted - 2005-01-13 : 08:12:05
Our database server is running SQL Server 2000 under Windows 2003 Server (the box has multiple Xeon P4s and 3Gb RAM), and has several databases stored on it. We also have a separate web server, again running Windows 2003 Server, and again running several web sites.

When one particular site comes under heavy load (100-200 concurrent users), the we start getting connection denied errors:
"[DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied. "
Obviously, this is a totally helpful error...

I don't think that it is the number of users, as we have a logging system logging every page access to our web sites, which is typically running at around 200-400 concurrent users. Plus, we never used to get this problem when running Windows 2000 - it's only appeared since upgrading to Windows 2003 (and site loading hasn't changed).

Looking at Performance Monitor, whenever this error happens, the number of active connections is very high (>100), but number of transactiosn, etc, is very low (<10).

Any ideas? (Googling for this error makes it seem like this is a problem with Windows 2003, as there are numerous mentions of it).

Also, does anyone know if/how you can see how much memory (not disk space) each database is currently using? (we'd like to see how much RAM each one takes at a given time, as the amount of RAM SQL Server is using is massively greater than the size of all the DBs...)

Thanks!

martinch
Starting Member

35 Posts

Posted - 2005-01-18 : 05:57:41
No takers?
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AjarnMark
SQL Slashing Gunting Master

3246 Posts

Posted - 2005-01-18 : 18:56:00
martinch, what do you get if you run this:

select *
from master..sysconfigures
where config = 103

That will tell you how many maximum connections you can have to the server. If it is set to 0 then that means 'no limit'. If set to something else, maybe you are exceeding the limit.

As for the memory issue, SQL Server will use as much memory as is available whenever it needs it. Activities like sorting can cause that to jump to multiples of what you might otherwise expect. This is one reason why it is recommended to run SQL Server on a server by itself so that it has access to as much memory as possible. Once SQL Server has taken hold of memory it rarely gives it up. Is this causing you some particular problem or did it just "look weird"?

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martinch
Starting Member

35 Posts

Posted - 2005-01-19 : 04:04:57
AjarnMark, thanks for the reply!

quote:
martinch, what do you get if you run this:
select *
from master..sysconfigures
where config = 103

It says that "value" is 0, and "status" is 2, so it doesn't look like it's limiting the number of connections...

quote:
This is one reason why it is recommended to run SQL Server on a server by itself so that it has access to as much memory as possible. Once SQL Server has taken hold of memory it rarely gives it up. Is this causing you some particular problem or did it just "look weird"?

Well, SQL Server is on a dedicated box, simply for that reason. We know it normally uses tonnes of memory, but even so, I guess seeing the memory maxed out set off some kind of instinctive "oh dear" reaction in us . The memory usage isn't causing any problems that I'm aware of - we would just liked to have known which DBs were having the memory allocated to them, out of curiosity more than anything.
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AjarnMark
SQL Slashing Gunting Master

3246 Posts

Posted - 2005-01-19 : 16:53:27
If you come up with a way to measuring this, I'd be interested. But my WAG would be that tempdb is the one that really uses up memory due to temp tables, sorts, etc.

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martinch
Starting Member

35 Posts

Posted - 2005-01-20 : 04:42:40
Thanks for the reply, AjarnMark! If I ever find out how to get memory usage by DB, I'll let you know (although I get the distinct feeling it's not possible...)

Has anyone else experienced the "DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied." error for seemingly no apparent reason? I ask because we didn't get it on our Windows 2000 server, but we do now that it's been upgraded to Windows 2003. As the only thing that's changed is the OS, does anyone know what could be causing this?
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afflack01
Starting Member

2 Posts

Posted - 2012-04-26 : 03:02:19
The only difference that it may have from the other machines on the network is that it may have extra memory, a higher speed processor and a bigger hard disk drive. In very large computer setups, there are server machines, which are different from the ordinary desktop. The difference is that they may have more than a single processor. They may have two or more processors. The hard disks of a server machine maybe SCSI hot swappable disks, or fixed hard disks.

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