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 How to Position 5 database server ?
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mailtonoorul
Starting Member

India
3 Posts

Posted - 06/04/2014 :  01:07:18  Show Profile  Reply with Quote
How to Position 5 database server for an centralized database for an application?

1) We are providing a e governance solution for an organization,where we are providing a centralized database,Client have provided 5 Database server for the same.how can we position the Database Server? there are 5000 Concurrent users and 25000 users,SAN Storage for approx. 60 TB,Database size of 2 TB and growth of 1 TB every year

2) How many instance can we have for above said Case?

3) How much RAM Required ?

Noorul Ameen

tkizer
Almighty SQL Goddess

USA
36653 Posts

Posted - 06/04/2014 :  12:12:09  Show Profile  Visit tkizer's Homepage  Reply with Quote
If there is only one database, then I would probably setup a 4-node SQL Server 2012 Availability Group. 2 nodes would be at the primary site, both sync replicas. 2 nodes would be at a DR site, both async replicas.

If there's only one database and if you use Availability Groups, then you would have a standalone instance on each replica.

Get as much RAM as can be afforded.

Tara Kizer
SQL Server MVP since 2007
http://weblogs.sqlteam.com/tarad/
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jackv
Flowing Fount of Yak Knowledge

United Kingdom
2011 Posts

Posted - 06/05/2014 :  01:36:03  Show Profile  Visit jackv's Homepage  Reply with Quote
@tara - if the primary and DR sites are close - would you consider synch replication between Primary and DR sites? This is assuming performance was acceptable

Jack Vamvas
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http://www.sqlserver-dba.com
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tkizer
Almighty SQL Goddess

USA
36653 Posts

Posted - 06/05/2014 :  12:14:36  Show Profile  Visit tkizer's Homepage  Reply with Quote
If performance is acceptable between two sites, then yes you can do sync. However, you can only have a total of 3 sync replicas (including the primary). That's in SQL Server 2012 at least, 2014 might give you more. I know you get more async replicas in 2014.

So in 2012 with a 4-node AG, you'd still need one async.

Typically the network latency between a primary and a DR site is too high to use sync. Even at 12-15ms (300 miles was the distance), the performance degradation was huge for us.

Tara Kizer
SQL Server MVP since 2007
http://weblogs.sqlteam.com/tarad/
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jackv
Flowing Fount of Yak Knowledge

United Kingdom
2011 Posts

Posted - 06/07/2014 :  01:59:59  Show Profile  Visit jackv's Homepage  Reply with Quote
Thanks for the feedback, I've recently been testing sync repliaction with about 25 miles and the performance has been acceptable. Of course, I'd like it to be quicker but the benefit gained , it's worth the slight degradation in performance.
Some applications tolerate the performance hit OK , but other , more time sensitive apps are not so tolerant. The unpredictability of the network is the biggest issue



Jack Vamvas
--------------------
http://www.sqlserver-dba.com
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tkizer
Almighty SQL Goddess

USA
36653 Posts

Posted - 06/08/2014 :  12:57:20  Show Profile  Visit tkizer's Homepage  Reply with Quote
Yeah we have very, very high performance requirements. I used to support a system that could not tolerate anything being over 300 milliseconds. It timed out at 300ms. Adding 12-15ms would have meant many more timeouts.

Tara Kizer
SQL Server MVP since 2007
http://weblogs.sqlteam.com/tarad/
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jackv
Flowing Fount of Yak Knowledge

United Kingdom
2011 Posts

Posted - 06/10/2014 :  01:42:07  Show Profile  Visit jackv's Homepage  Reply with Quote
In those situations ,we've implemented - similar to above - i.e sysnch replication on one site , asynch to the failover site. With a very level of monitoring. Aiming to keep variability as low as possible

Jack Vamvas
--------------------
http://www.sqlserver-dba.com
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