Mirroring, Snapshot Replication, Load Balancing And Other BIG Questions
Mar 22, 2006
You will all have to excuse my ignorance. I'm a developer who also doubles up as a development DBA. I am however not particularly knowedgeable about all the really important DBA stuff.
We've built a small BI solution using SQL Server 2000. Our problem is that our server is getting on in years (5) and doesn't really have enough disk space or grunt. We havce a number of summary cubes that we've optimised quite successfully but our billing line level cubes run to 60 million rows and, well, they're about as quick as a dead ferret. Especially given the stupid queries our data analysts keep running.
We have however proved our point. That this can be done and indeed SQL Server can do it. So we're now looking at some infrastructure spend and some new copies of SQL2005.
But i need some advice. Our user base is climbing through the roof, we originally had 10, now we have closer to 50 and at this rate it'll be a couple of hundred by the end of the year. We're using a plugin called XLCubed to deliver that data into Excel from the Analysis Server.
The OLTP database that sits behind it is fairly robust but we have a number of web based apps (mostly lookup systems) that want to use the nice shiny new accurate tables of data we have created.
So I'm looking at a fairly big server to hold the OLTP DB, this will also serve up live data to our web apps. Its worth pointing out that the source data system is a batch system that processes overnight so we load data from yesterday at 6pm each evening and process our cubes and stuff overnight. Thus the data is a couple of days out of date. Don't laugh they used to use MS Access and got one mangy data set a month so this is a massive leap forward.
I wanted to mirror the DB to another machine but I also want to have a separate Cube Server. I wondered if the cube server could use the mirror to read its data from as opposed to loading the Main Server (the mirror would be an identical box) we would also have a separate box running some of our other systems acting as the witness.
I also wonderd about exporting the Cubes onto file shares for use locally as opposed to via the server which is how they connect now.
We have been using Reporting Services and some of the queries the devs write are not exactly efficient. So I was also planning on clustering a pair of smaller servers into a reporting farm. Could I use another SQL Server to serve data up to them? Could I use a DB snapshot to copy the data required to this server? What are the time / size implications of using a snapshot and replicating it over each night?
Any suggestions for places to read up on this? I've looked at the MS marketing blurb and while its big on buzzwords its light on specifics. Like how it actually works and how you would actually configure it to do some of this and what the implications would be.
Any advice?
many thanks
Steve
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Apr 27, 2007
Hi guys, can I know whether 2 servers (load balancing) able to set up the mirroring on another server? From what I know, mirroring only can set 1 IP address for principal. I just want to double confirm on it. Thanks for any assistance here.
Best Regards,
Hans
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Nov 3, 2006
Is it compatible to set up SQL DB mirroring on 2
different physical servers (High availbility + FULL transaction safety +
Automatic failover with a third server as witness) and simultaneously set up
network load balancing between these 2 servers (option with Windows Server 2003
Enterprise) ?
If yes, which type of licenses do I need and how
many (for SQL server 2005 and Windows Server 2003) with such a configuration
?
- 4 physical servers in total : A, B, C and
D
- load balancing between A and B (same application)
- load balancing between C and D (same application)
- A hosts principal DB X, B hosts mirror of DB
X
- C hosts principal DB Y, D hosts mirror of DB
Y
- D is witness for A and B
- B is witness for C and D
- A and B : only internal clients <
25
- C and D : both internal and external clients
(internal clients <25, number of external clients is unknown (>25)
)
Hoping this description will be helpful enough for
you...
(I am looking for a very high availability
system)
Thank you in advance for your support.
This licensing question is pretty much urgent (for
a bid) : a quick answer would be very appreciated...
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Jun 14, 2007
Hello.
I am confuse and cant decide on how to setup high availability on our SQL 2005. Here's what on my mind and on resources list:
I plan to have mirroring on my SQL1 to SQL2 with the help of SQL3 as witness. So this would be automatic failover. My idea on mirroring is when SQL1 goes down, SQL3 would tell SQL2 to run and be the primary. It will automatically failover to SQL2. Right? My questions are:
1) How can I revert back to SQL1 once it is ready?
2) I read in one of the post that it is impossible to write in a mirrored DB, is this true? I mean, what's the use of failing over to the next node when it's not possible to write and update data/records?
3) If number 2 is false (i hope so), how would the data be synchronize from SQL2 back to SQL1. Those transaction that were made while SQL1 is down.
4) How about the connection string from the web applications? Would it be automatically point to SQL2? We have load balancing setup in place, would this help web application connection to automatically point to SQL2?
Another setup:
We have SAN in place (not yet used, but is planning to use for this SQL thing), EMC to be specific. My question would be:
1) For SAN setup, the data storage would be centralize. So would that mean that SQL1 and SQL2 services will use the same data and log file from the SAN storage?
2) How would you call this setup then? Can this be clustering type of high availability? Will clustering work under load balancing setup? I believe mirroring is not possible here? Right?
3) How can I setup my 3 SQL servers with the same theory in mind: when SQL1 goes down, SQL2 will take over. Data will be synchronize when SQL1 is up and running again. With automatic failover and reverting back to primary.
I read so much topics about this, but the more I research, the more I get confuse.
Any suggestions, comments, advice is greatly appreciated!
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Aug 28, 2007
All,
We have SQL 2005 db mirror configured with a witness server for high availability. Node 1 is the principal and Node 2 is the mirror. A nightly job creates a snapshot on Node 2. The snapshot is used for previous day reporting queries. We have now been asked to present another copy of the database for near-time reporting. I thought about possibly adding a peer-to-peer replication as part of my environment but was hoping to see what everyone else out there is doing.
Regards,
Ian
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Feb 27, 2006
Hello,
How is load balancing working in SQL Server 2000. We want to have two different servers as a back end for our web based eCommerce application. Is this possible? While there be any modification requirement in the application?
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Nov 6, 2000
What is the meaning of Loadbalancing and how can I use this term to my advantage.
Q2. How would I know that I need to do load balancing and how can I set it up.
I have wrote load balancing in BOL and did not get any thing on it. can anyone refer me to where I can read more about it.
thanks
Ahmed
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Dec 14, 1999
Hi All,
We have a Intranet Application which uses IIS / SQL Server 7.0, we are trying to support the application for 30,000 + users.
Since SQL Server can only support upto 32676 user connections (Theoretically), is it possible achieve this with clustering / dynamic load balancing. Does MSCS and SQL 7.0 support this. Any other ideas, 3rd party software etc?????
Any input will be of great help.
Thanks
NK
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Jul 20, 2005
How much traffic/load can a database server running MS SQL server takebefore it can't handle it anymore? And when that time comes, what are therecourses? Am I able to load balance it between separate servers?
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Sep 9, 2007
need advice for below scenario
currently am having a active / passive cluster sql 2000 server, due to the amount of transactions am moving to new high end servers with sql 2005 cluster.
incase the new cluster also doesnt stands the load what approach i should use similar to load balancing.
with regards
alby peter
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Apr 18, 2008
I want to know about Data Base Load balancing work. How to do that? I want to know that.
Please help me........
Reagrds
Binod Kumar Tiwari
+91 9958680044
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Aug 14, 2007
Why SQL Server 2005 Dosn't Supoort Load Balancing?
I think Load Balancing is a feature of great necessity.
Would it be probably added to other features in Next versions?
thank every one
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Jan 25, 2006
HiOn our SQl Server (2000) we can have queries that take at least 10-20mins(require full table scan fo billion row table). When one of these queriesis running it substantailly slows down very quick queries (sub secondqueries take several seconds).I believe there is no way to set priorities but was wondering if thereare other configuration settings that could help. The server is dualprocessor so maybe setting maxdop to 1 will help. Memory size isdynmaically assigned up to 4Gb but as the DB size is > 1Tb I'm not sureif allowing this much memory is actually decreasing performance when thequick query trys to get through.Any suggestions.ThanksMike
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Nov 30, 2007
need the concpet of load balancing cluster ?can any one help me out with any link....?
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Jul 20, 2005
When a web application becomes overloaded with traffic, one can offload itby load balancing and clustering the front end web servers. What happenswhen the back-end MSSQL database becomes overloaded? Does MYSQL offer loadbalancing and clustering?
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Apr 10, 2006
Hi,
We have a massive database that users run complex queries on. The queries are never the same so caching cannot be used too much effect. When many queries are run at one time by the various users the system slows down.
What we are trying to achieve is maybe have a primary SQL Server 2005 machine and multiple (4-5) SQL Server 2005 secondary machines. The primary machine would get the query and would decide based on loads as to which secondary machine would fulfill the query.
We are not worried about failover and clustering and all that fun stuff. Our primary concern is to achieve the quickest execution of the query. We were wondering if SQL Server 2005 has any feature that enables query load balancing of some kind.
Thanks
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Jun 7, 2005
Hi!Currently we only have one SQL Server database in our production system. I would like to add one more SQL server 2000 database. I would like to configure them so that both server share the load and Failover. I did some research and I found that I can do this by installing the OS (Windows 2000 Server Enterprise Edition) and SQL 2000 Enterprise Edition on both machines using the windows clustering. I want both servers to be active. They both have a copy of the production data. What I don't know is that, if it is possible to synchronize the data on both databases using SQL Server Replication utitlites. From what I know one SQL Server must be Publisher and one Subscriber. Can one sql server be both? Because I want both sql server to be identical. Can I set up replication between more than 2 servers? We just need to add one server for now but I would like it to be expandable. In the future we may need more.So Please provide me some ideas and answers about the following.1- Can two SQL Server cross replicate (both update each other in order to be identical)?2 -Does replication work beyond 2 servers.?3- If you were to set up a production database; what do you recommend considering the load balancing and Failover using Windows 2000 Server Enterprise Edition and SQL Sever 20000 Enterprise Edition?Thanks,Michael
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Oct 15, 2007
We are looking at expanding our web application (C# and Sql Server). The module we are going to be adding will be far more processor intense (plotting and modeling) than any of the current code.
I need to know what the best design for this add on would be.
Would it be better to
a) Keep the new module as part of the core db (entire application on 1 database) and use loading balncing between 2 (or more) servers to handle the huge increase in demand?
b) Create the new module as a seperate database that runs on a seperate server?
If B is the best option (I am thinking it is not) is there a way to write easy and efficient queries and views of the 2 databases as 1.
Thanks
Justin
Justin Bezanson
www.justinbezanson.com
www.geekdaily.net - web development and technology blog and news
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Nov 6, 2006
i have a table with 10,000,000,000 records and i need Select and Insert many
records from or into this table in less than one second.
i can't buy a very expensive hardware(Server) for this SQL Server 2005
but i can buy many medium price hardwares(Servers) for this SQL Server
2005.
how can i distribute or cluster this table between many hardwares(Servers)?
note: i have few users (maximum 5 users) for my database but i have a
very large table and Sql server 2005 server need to respond to this
users in less than 1 second.
i want to distribute this huge table in seperated hardwares. becuase i
can't buy a very expensive hardware from my server but i can buy many
medium price hardware for my server.
note: i need this: when a user run a select query on this huge table
his/her request distribute between many hardwares not one hardware.
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Jun 29, 2006
I am trying to achieve load balancing through service broker.
I have a 3 server setup:
server1:
Source Database where the requests are sent. This has two routes created on this to server 2 and 3 with the service broker instance id specified. The service broker matches both these routes to the destination databases on Server 2 & 3 and send the requests in a round robin fashion by itself.
server2 & 3: These servers have the destination databases. The databases are exactly same with same messages, contracts, queues, services, and servicing programs. These don't send the responce back and the source is also not expecting for any response from the target databases.
When I tested this scenario it was behaving in a different manner. If there are 20 requests, in a normal case 10 requests should go to either of the destiantion servers, but I found that sometimes it was 11-9 or 12-8 only once did it do a 10-10.
Also I want to know is it best practice to rely on the inbuilt feature of the service broker in matching the routes and sending the messages rather than doing it ourselves. I which case one has to write the logic for sending the message to appropriate target server based on the status of the destination queue.
I also want to know which would be the best technique to use to bring the two destination databases in a concurrent state.
thanks
ashok
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Nov 8, 2001
Hey guys,
Lately we have come across a problem where our application is undergoing some extreme load against the SQL 2000 server database we have setup, where the server is hitting 100% CPU utilization each time. Currently the box is a 2 processor box.
Here is the question I have. I have seen under most SQL Server clusters that an active/passive setup is implemented. Where the passive server just exists as a failover mechanism. What I am looking for is some information on how to setup active/active setup where each server receives processes to handle.
Has anyone created a setup like this? Are there any standard benchmarking tools that can be used to see how this configuration increases performance? Is this setup more favorable than going to a 4 processor server as oppossed to our current 2 processor server?
BTW: We have noticed that after a web application where the user sits idle for a while the SQL Server application loses the connection with the application user...Is this the SQL Timeout causing the connection to disconnect?
Thanx for any response...
Bri
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Jun 13, 2014
Is there such a thing called 'Load balancing' on fail over cluster?
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Aug 28, 2014
We are having a conversation at work and the subject of load balancing with SQL came up. Right now we are running SQL Server 2014 on four (4) machines. I am using a AlwaysOn with Availability Groups (AG). Now I know that we can scale out the reading in AG by allowing the secondary serves to receive reads.
Is there a way to be able to do this with writes? Can I have in essences 2 masters that some how reconcile with each other? We are expecting a huge amount of writes in the near future and we need a way for SQL to handle the amount of traffic we are expecting with out any issues.
I explored the possibility of Peer - to - Peer replication; however, it seems that it would be more work if we are constantly making updates to the database scheme.
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Jul 7, 2007
I have posted this also in one forum. Somebody might have idea here.
We have four Windows 2003 advance servers with SP 3 configured on NLB.
Each of them has one NIC.
Recently we started to get frequent time-out error messages from web applications on those servers when they try to establish the connection with the SQL 2005. If you run web pages application to connect to sql server 10 times, 9 times you will get good connection results and 1 time you will get time-out.
Microsoft OLE DB Provider for SQL Server error '80004005'
Timeout expired
/common/mypage.asp, line 20
Connection to sql server is established with the connection string. Any idea how to solve this problem? Is there a connectionproblem? from NLB to Web to SQL?
We have tried doing some suggestions (e.g. LMHOST, IP, domain account for WEb to SQL connection, the Query Wait in SQL advance property.), but seems this timeout expired still exist
Thanks in advance...
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Feb 28, 2005
Hi,
I have two sets of data i.e two instances of SQL server in two different cities. Data entry happens at both the places.I need to balance the data in two servers i.e. I need to Synchronize the data.
Currently I am Exchanging the data between two sides and using a Buffer database to update the incremental infromation.(Running a SQL script).
I have GUID columns in my database. I am too new to replication.I wanted to know whether I can implement repliaction and what changes i need to make?(e.g. Replacing GUID columns with Identity columns).
Permanent connectivity between two databases is required or Replication can be performed whenever connected?
Best Regards
Rohit
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Feb 2, 2007
Hi guys, does anyone get this snapshot on mirroring. My mirror server had been down for 1 month+ and just up again. Then my principal server will automatic synchronizing with it. Once i create snapshot on the mirror server for checking whether it get the latest record, there's an error msg which shows 'The database must be online to have a database snapshot.' Then I leave it for 1 hour+ for synchronizing and then still the same. Can I get any solution of it? Thx for the assistance.
Best Regards,
Hans
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Jun 22, 2006
Hi, I was wondering if changing the schedule of the snapshot agent will do any effect the unc/snapshot files ? I'm now doing merge replication and i am applying snapshot from alternate location. If i change the schedule do i need to re run the snapshot agent ? I'm afraid that the current snapshot will be expired..
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Dec 13, 2006
Scenario: The principal is in LA and the Member is in NY.
1. Where should the witness typically reside LA or NY?
2. Can the witness handle several quoroms or it has to stay within the quorom it is assigned to?
3. LA to NY - what is the recommended bandwidth for this? right now we have a 1MB pipe? We average about 9 Gig of transactions/day
Thank you..
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Nov 3, 2006
Following a bunch of tests I've concluded that mirroring works very well, even in sync mode the perf impact is low. Log shipping integration is clean following failover. Excellent stuff, thanks. However there are a few things that would make it a much better sell against competetive solutions:
1. It's my experience that Database Mirroring in HA mode effectively only supports one failure, so if your Witness goes bang you lose auto failover capability. If the mirror then fails you lose database service. This makes robustness requirements for the Witness very important. Are there any plans to allows multiple witnesses with some form of active/passive failover between them? I seems a little over the top to have to consider clustering a witness.
2. It's extremely irritating that we can't create logins on the mirror if the login has the mirror database as their default database, just because the database is in recovery; I mean it not as if the db doesn't exist. Can this be addressed with the security team, perhaps masking the error somehow if the database can't be opened ? Bear in mind the database principal will already exist in the mirror database as it will have been created on the principal server, all we need is the output from sp_help_revlogin from the principal server to match up the sid and password.
3. If number 2 is addressed, it would be possible to build a more elegant and robust sync mechanism using service broker, without having to rely on alerts to then create any missing logins on failover. Are MS looking at building something to address login synchronisation of the failover servers, perhaps using service broker? Seems for a supposed HA solution this is a very untidy missing piece and with some environments which might not be able to rely on using Windows groups (sql logins), it makes rapid failover difficult.
4. It would also be useful, while on the subject of number 3, to provide some mechanism for, at least, auto-checking configuration/msdb differences between servers and reporting these, if not provision for keeping them in sync. I appreciate that not all systems will want exact matches between the partner servers, but at least providing mechanisms to sync them up would help.
5. Any plans for supporting multiple mirrors? Even async? Would make for reporting provision using snapshots much cleaner as the main mirror could be left alone for HA.
thx,
Simon.
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Apr 25, 2007
Hi guys,
I have read many articles on the matter and I have probably used up all my printer's ink in doing so, however, some questions still remain.
1) What happens if I have to reboot the mirror.. security update, etc.? Obviously the session is broken during reboot, but would I have to do another backup of the principal and resync everything?
2) I know it is not best practice but at this point I have no choice, however, I wanted to get your guys feedback on having two instances of SQL2005 on my development box. One for the mirroring of the production and the second for development. The two instances would live on their own drive... not partitioned and have adequate memory and space.
What would I have to look forward with this?
3) Lastly, I am still uncertain if mirroring is approved for production. Is it?
Thanks for your help.
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Jan 31, 2006
Our company is looking to move to a more robust database platform/setup, and it looks like sql 2005 + database mirroring is what we are looking for. First I have some questions about it.
Can a server that is functioning as a mirror for one database be the primary server for a seperate database? Basically think of a triangle of three sql servers, each serving as a primary server for a specific database, and using the next server in the triangle as a mirror for that specific database. To be more specific:
Server 1, Primary Database A, Mirroring Database C
Server 2, Primary Database B, Mirroring Database A
Server 3, Primary Database C, Mirroring Database B
If that is possible, how many witness servers would be needed to accomplish the above topology? On that note, how robust hardware wise should the witness server be?
On a completely seperate note, what method is recommended for interconnecting these servers? Is gigabit ethernet fast enough, or does it require something like fibre channel or infiniband?
Thank You!
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Feb 16, 2006
We are planning to update our two node, active/passive clustered system to SQL 2005 from SQL2K. Would we be better off to use database mirroring rather than clustering with failover? I believe mirroring takes 3 systems rather than two (one for each mirror and one for monitoring), but can the monitor be a rather low powered PC?
Our current cluster uses two 4-processor Dells and an external PowerVault RAID array with fiber channel connections. Each server has two NICs, one for general network and one for heartbeat and a fiber channel card to connect to the external PowerVault.
Here are my questions:
1 - If I understand it correctly, mirroring uses just separate servers without the need for the rather expensive and complicated shared fiber channel array that must go between them. Do I still need a shared array or can I just use internal RAID arrays in each box?
2 - Are there any advantages to keeping our current system? Our current system has worked well, but the failover takes a couple of minutes. Is mirroring faster?
3 - Is there still a virtual IP address and network name that everyone connects to?
4 - What are the drawbacks?
5 - Can I run non-mirrored DBs on the same servers or are they really locked together tightly?
6 - How much different in configuration can the two boxes be? With the cluster, I really need duplicates in every way.
7 - Do I need a separate license for the SQL Server on each box in the mirror or is one enough, since they work in lock step?
Thanks for any of your experiences on this.
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May 26, 2015
What is the main difference between snapshot and transactional and merge replication?
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