Re: High availability

Just to clarify that some. Geoff is 100% correct in that SQL Server does not
have the implementation of multiple dbs such as Oracle Rac. But as I eluded
to earlier there are two types of replication that you may have heard of
that some people relate to this. This is Merge and bi-directional
replication. Each allows multiple SQL Servers to have a full or partial copy
of the db and has the ability to update the others with changes. But this is
not typically a scale out solution for performance so I am not advocating it
just making you aware of what SQL Server has to offer and hopefully avoid
some confusion.

--
Andrew J. Kelly SQL MVP

"Geoff N. Hiten" <SQLCraftsman@xxxxxxxxx> wrote in message
news:%23q0Z6N8wHHA.3756@xxxxxxxxxxxxxxxxxxxxxxx
There are no native multiple-master database implementation technologies
for SQL Server.

--
Geoff N. Hiten
Senior Database Administrator
Microsoft SQL Server MVP





"Suri Nagarajan" <SuriNagarajan@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:91A0A7A4-536D-45AF-8C7E-CCFAE8C43CB9@xxxxxxxxxxxxxxxx
I think you are right regarding scaling up, now I have to convince my
client
to invest in bigger and better hardware for hosting the database, not one
but
two or more of similar hardware for fail over server. Thanks for the
info,
it was really useful.

But just for my understanding - in SQL server is there an implementation
like Oracle to have multiple master database in different servers with
each
database mimicking the same tables,structure and data which gets
automatically synchronized among themselves, so that different users can
connect to different servers and still be looking at the same data?

"Andrew J. Kelly" wrote:

I have worked on many systems with thousands of users on a single server
with no problem given the right configuration. Both scaling up and out
have
pros and cons but unless the system is read only scaling out is much
more
difficult than scaling up in most cases with SQL Server. These days you
can
scale up to a 64 processor system with 1TB of memory so hitting the max
performance limits are pretty hard to do if done correctly.

--
Andrew J. Kelly SQL MVP

"Suri Nagarajan" <SuriNagarajan@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message
news:5AA822BD-FD7A-47A5-8D01-9455D22C2149@xxxxxxxxxxxxxxxx
Yes, I did think of scaling up as an option. I have been dealing with
DB2
and Oracle based systems in the past , I recently took over this SQL
server
based system, I am trying to understand/explore all options available
(since
I am not sure about the options available in SQL server environment).

Currently we are dealing with user environment with couple of hundred
users
which is not a problem, the application is running smooth. But in the
near
future this system has to be deployed in an environment where couple
of
thousand users will be accessing the system (huge jump in volume of
data
and
number of transactions).

I feel if I scale up, we will be hitting the max performance limits
soon
due
to sudden increase in number of users. I think scaling out will be
more
flexible to add more power in the future if needed. Both High
availability
and performance are critical requirements since its an on-line
transactional
system.



"Andrew J. Kelly" wrote:

FYI, Replication can be used for non-read only servers but is usually
not
a
good choice for scaling out in order to get performance gains. You
need
to
separate the two requirements (Performance & High availability)
somewhat
as
they are typically two completely different solutions or approaches.
What
is wrong with scaling up? How large is the server now and what do
you
need
to support? And are you sure it has been tuned properly? You might
not
even
have the need to scale up or out.

--
Andrew J. Kelly SQL MVP

"Suri Nagarajan" <Suri Nagarajan@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message
news:BEFF51E6-28E0-4784-A24C-0DBB2C4B497F@xxxxxxxxxxxxxxxx
I am new to SQL server, I would appreciate any help on following
question.
I
tried researching and found few options (detailed below after the
question)
which didn't really help what I am trying to do. Any suggestion for
the
Gurus
will be helpful.

I am trying to implement a high availability system which will have
very
high database access traffic - potentially couple of thousand users
trying
to
access a transaction system (read and/or update by most users).
Unfortunately this is not a new system, its an existing system with
around
200 tables implemented in a single server (Using SQL server as
database),
due to increase in number of users and traffic I need to find ways
to
increase availability and performance.

My final system should be implemented on multiple servers and each
server
hosting SQL server databases (same data, tables and structures) but
they
should be automatically synchronized to have same data (just like
multiple
masters in Oracle) so that different users can be connected to
different
server (for load balancing and performance improvement . Is this
possible
in
SQL server?

I tried following options

1. SQL server clustering - this can only be used for fail over not
as
multiple synchronized master databases.

2. Replicated server - replicated server can be used only for read
not
for
updates

3. Federated database design with distributed partitioned views -
but
its
difficult to split certain databases across servers due to
complexity
and
number of Foreign key constraints defined in the system.


Thanks in advance for suggestions/help.

Regards,
Suri.










.

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