Search results matching tag 'Database Mirroring'

High-Availability White Papers and Resources for SQL Server

KKline — Thu, 26 Jul 2012 15:00:00 GMT

In foreground, attendee makes dreaded "shoot myself" hand sign to the speaker.

I was just telling the good people of Charlotte about how they (and how YOU) need to read all things by Paul Randal (blog | twitter), except for all of his cheesy romance novels like Caress and Conquer written under the nom de plum of Connie Mason.

There's lots more good stuff from Paul, just not romantic.

This is a 'so-last-version' whitepaper describing five common high-availability and disaster-recovery architectures deployed by customers, along with a case study of each. Although the white paper is specific to SQL Server 2008 R2 and isn't updated for AlwaysOn features, it's still really, really good. It covers:

Failover Clustering for High Availability with Database Mirroring for Disaster Recovery
Database Mirroring for High Availability and Disaster Recovery
Geo-Clustering for High Availability and Disaster Recovery
Failover Clustering for High Availability Combined with SAN-Based Replication for Disaster Recovery
Peer-to-Peer Replication for High Availability and Disaster Recovery

You can get it from this link. Not everything is transferable to new AlwaysOn technologies, but then again AlwaysOn is an Enterprise Edition feature. So the database mirroring recommendation can be upsized, in many if not all cases, to SQL Server 2012, while the SAN and peer-to-peer recommendations continue to hold fast.

In addition, I encourage you to get up to speed on AlwaysOn. There are two great AlwaysOn FAQs that I recommend. The first is Microsoft’s official AlwaysOn FAQ at http://msdn.microsoft.com/en-us/sqlserver/gg508768.aspx. The second comes from my buddy and high-availability expert Allan Hirt (blog | twitter) at http://www.sqlha.com/2012/04/13/allans-alwayson-availability-groups-faq/.

To get started with AlwaysOn, check out http://msdn.microsoft.com/en-us/library/cc645581.aspx.

Enjoy,

-Kev

Review the New Migration Guide to SQL Server 2012 Always On

KKline — Mon, 25 Jun 2012 16:19:00 GMT

I had the pleasure of meeting Mr. Cephas Lin, of Microsoft, last year at the SQL Saturday in Indianapolis and then later at the PASS Summit in the fall.

Cephas has been writing content for SQL Server 2012 Always On. Cephas has recently published his first whitepaper, a migration guide to SQL Server AlwaysOn. Read it and then pass along any feedback: HERE

Enjoy,

-Kev

-Follow me on Twitter!

Microsoft SQL Server High-Availability Videos and Q&A Log

KKline — Wed, 01 Dec 2010 22:11:00 GMT

You Want Videos? We Got Videos!

I always enjoy getting the chance to catch up with author, consultant, and Microsoft Clustering MVP Allan Hirt. Allan and I recently presented two sessions covering an overview of high availability in Microsoft SQL Server and, the following week, a demo of how to implement several different kinds of high availability techniques including database mirroring, transactional replication, and Windows clustering services.

You can see videos of these presentations at the Quest Software Pain of the Week webcast site.

Archives of other videos are here.

We're joined by my new cohort in crime, Iain Kick, also renowned for his role as the editor-in-chief at SQLServerPedia.

Allan is the author of these and other books: ...and...

During the Q&A, we always get a lot of questions. Here are the collected Q's and A's.

~~~

Meeting Questions and Answers: Subject: Pain of the Week We -

October 14, 2010 Start Time: 14 October 2010 16:00:00 GMT+1:0

________________________________________

Paul T Asked: General comment..... copying files is where I love the SAN replication. Don't trust it at all for real database stuff though!

________________________________________

Sherbaz M C P Changes Question To: Please suggest the best back/restore techique for huge databases. Should we go for SAN level backup technologies or snapshots that uses SQL Writer? Storage admins claims that they can restore a 28 TB database in 30 minutes. They are saying that they can even take transaction log backups and restores.

________________________________________

Ameena L Asked: When we talk to our management about SLA, Recovery object and uptime etc. They say just do your best. They expect no downtime but will not define any of this so how we determine what we are shooting for if target is not identified?

Kevin Kline Answered: That's why actually working through a recovery is so important. I strongly recommend that you perform a full recovery, perhaps to a dev or QA server, and then using that benchmark as the general rules for your SLA.

________________________________________

Stuart A Asked: What do RTO & RPO stand for?

________________________________________

Fadel Asked: at 2 part questions: part1- what is the advantage of having a sql clustering over Oracle RAC where in the first case, we have at least 1 node sitting there doing nothing waiting on the other node(s) to fail, comparing to the second case where Oracle RAC offers both, HA and scalability - part2: what is the new features on sql 2008 clustering compared to sql 2005 clustering - thanks!

________________________________________

Mohammed Changes Question To: Shouldnt clustering considered as a local HA instead of DR since the other nodes are local?

________________________________________

Alan Xu Changes Question To: Is cluster 2008 support sql 2005 instance and sql 2008 instance in the same cluster?

________________________________________

sjohn Asked: What is the maximum recomended distance for a synced mirroring with a reasonable size of pipe

________________________________________

Anita Asked: You mentioned about multi - instance cluster( active-active)? I will be interested in learning more about this. we have active-active in our environment. Is it scheduled for next week?

________________________________________

robert l Asked: Will mirroring work with a large number of "Smaller" databases? 500 2gb databases vs 2 1tb database

________________________________________

Alvinator Asked: When log shipping if you have a large tlog will it ship it in chunks or the entire log file?:

________________________________________

James M Asked: What are the advantages of Database Mirroring over transaction replication? or vice versa

________________________________________

Martin Asked: IDEA - Maybe Quest should provide a Database Invenotry/Request to gather all the information for a HA environment

________________________________________

Martin Asked: I am very interested in finding a holistic view to HA and DR to handle SQL Server. Oracle and even DB2 - are you aware of such a product/s?

________________________________________

Alan X Changes Question To: How to handle SSIS in multiple instance?

________________________________________

Nadim Y Asked: I was coming from a consolidation angle - looking to install muliple instances on each node within the cluster. Is there an upper limit or just based on the resources available on the nodes

________________________________________

Mohammed Asked: IS clusteting possible in std edition sql 2008?

________________________________________

Anita Asked: You mentioned about multi - instance cluster( active-active)? I will be interested in learning more about this. we have active-active in our environment. Is it scheduled for next week?

Kevin Kline Answered: Next week is mostly demos of how to set up these techniques. However, there are some resource slides at the end that point you to more websites and whitepapers about each of these specific technologies.

________________________________________

robert l Asked: Will mirroring work with a large number of "Smaller" databases? 500 2gb databases vs 2 1tb database

Kevin Kline Answered: absolutely! however, there is some management overhead in that mirroring is configured on a per database level

________________________________________

Alvinator Asked: When log shipping if you have a large tlog will it ship it in chunks or the entire log file?:

Kevin Kline Answered: It doesn't ship the transaction log, it shipps the backups/dumps of the t-logs. That's an especially good use for backup compression. We have a lot of features specifically for this in our LiteSpeed backup tool.

________________________________________

James M Asked: What are the advantages of Database Mirroring over transaction replication? or vice versa

Kevin Kline Answered: We're on those slides now. =^)

________________________________________

Martin Asked: IDEA - Maybe Quest should provide a Database Invenotry/Request to gather all the information for a HA environment

Kevin Kline Answered: I like it, Martin. I'll put that in my notebook. Btw, have you seen our "Discovery Wizard for SQL Server"? It does inventorying for SQL Servers.

________________________________________

@SQLRich Asked: I've heard that not all of the SQL components are cluster aware, is this true?

Kevin Kline Answered: Yes, afaik, SSIS is one of the biggest offenders in this area. But I think there are others.

________________________________________

Desi Asked: Can you mirror a database to more than one locaton?

Kevin Kline Answered: I don't recall the exact steps to do this, but yes. Also available with replication and log shipping.

________________________________________

Mohammed Asked: IS clusteting possible in std edition sql 2008?

Kevin Kline Answered: Discussed on slide 11, Mohammed. :-)

________________________________________

sjohn Asked: What is the maximum recomended distance for a synced mirroring with a reasonable size of pipe

Kevin Kline Answered: That's on slide 10, :-)

________________________________________

Nadim Y Asked: Is there a maximum number of instances you can have in a multinode cluster

Kevin Kline Answered: Not sure what you mean, Nadim. Usually, I don't see more than 2 actives to 1 passive.

________________________________________

Mohammed Asked: One question before we leave please..i asked this before also. Clustering is more Local HA and mirrroing/ls is DR...is this correct?

Kevin Kline Answered: Clustering across fibre can be miles, sometimes many miles distant, though it's uncommon. Mirroring and log shipping can be long-distance. Latency varies per technology type and is also another issue as to whether the solution is considered HA or DR.

Database Mirroring: FQDNs are Your Friends!

Adam Machanic — Thu, 14 Jun 2007 00:09:00 GMT

On a recent project for a customer, I learned an imporant Database Mirroring lesson: fully-qualified domain names (FQDNs) are essential!

Both Books Online and the mirroring wizard indicate that it's OK to specify the participating servers as IP addresses--so that's what I did. The witness came up fine, and the principal came up fine. Mirroring started, and I did a few manual failovers. Great!

But now I added the witness server and suddenly things started breaking down. The mirror instance couldn't connect with the witness, and the witness was throwing strange errors like:

Database mirroring connection error 4 'An error occurred while receiving data: '64(The specified network name is no longer available.)'.' for 'TCP://Server2:7024'.

...where "Server2" in this example is the mirror. Notice that the error doesn't include the IP address, but rather the server's name?

After banging my head against the table for a day or so, I wrote to about 50 people asking for help. No answers, and I thought I was out of luck until Don Vilen was kind enough to reply. Turns out, the problem is simple to fix: Don't use IP addresses, ever. Always use FQDNs! Thanks, Don!! Once the FQDNs were used, instead of the IP addresses, everything came up as expected and automatic failovers started working perfectly.

To find your server's FQDN, you can use "ipconfig" from the command prompt, and append the server name to the connection-specific DNS suffix.

I hope this post helps someone else avoid the frustration I went through. It was a rough couple of days trying to debug this problem and having to tell a customer that their planned HA solution might not work is not a fun situation to be in.