Level 6: Analyse & Deploy an AlwaysOn Availability Group

  • Perry Whittle

    SSC Guru

    Points: 233771

    Comments posted to this topic are about the item Level 6: Analyse & Deploy an AlwaysOn Availability Group

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    [font="Tahoma"]"Ya can't make an omelette without breaking just a few eggs"[/font] 😉

  • yusufkothari

    SSC Enthusiast

    Points: 134

    Hi - Perry

    Do you have documentation for backups on AlwaysOn 2012 database server.

  • Perry Whittle

    SSC Guru

    Points: 233771

    I have not covered backups in detail as there will be varying preferences involved. I may do something post the stairway series.

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    [font="Tahoma"]"Ya can't make an omelette without breaking just a few eggs"[/font] 😉

  • yusufkothari

    SSC Enthusiast

    Points: 134

    can you point me to any online resource in meantime...

  • prince_william

    SSC Enthusiast

    Points: 119

    Are there prerequisites to location of the failover cluster nodes in AD? I have seen cases where I need to move all nodes and cluster objects to COMPUTER OU for the wizard to work. Have you seen this happen?

  • yusufkothari

    SSC Enthusiast

    Points: 134

    No, I have not seen that situation

  • Perry Whittle

    SSC Guru

    Points: 233771

    prince_william (3/25/2015)


    Are there prerequisites to location of the failover cluster nodes in AD? I have seen cases where I need to move all nodes and cluster objects to COMPUTER OU for the wizard to work. Have you seen this happen?

    have your domain admin pre stage the computer accounts in the chosen OU and ensure permissions are applied, you should not have any issues afterwards

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    [font="Tahoma"]"Ya can't make an omelette without breaking just a few eggs"[/font] 😉

  • Perry Whittle

    SSC Guru

    Points: 233771

    yusufkothari (3/25/2015)


    can you point me to any online resource in meantime...

    Not at this present time, there are numerous scripts available

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    [font="Tahoma"]"Ya can't make an omelette without breaking just a few eggs"[/font] 😉

  • g.britton

    SSChampion

    Points: 13682

    Hey Perry,

    Any general recommendations on network latency vs synchronous/asychronous AOAGs? e.g. if the link between two dbs has a network latency of 10 ms, is that too long for sync? How about 100 ms, 1 sec, etc.?

    I know the answer could be "it depends", but I'm hoping some ball park estimates as guidelines. So far I've failed in my search for such in Microsoft docs.

    Gerald Britton, MCSE-DP, MVPToronto PASS Chapter[/url]

  • george sibbald

    SSC Guru

    Points: 104200

    Hi Perry, thanks for article, most useful.

    I have just configured our first multi subnet AG and have a couple of questions. I note on the listener tab you have specified port 5023, is this because that's a port used in mirroring, would you not use the same port the SQL service is running under? Does it matter?

    As I have multi subnets (two) I have two IP addresses for the listener resource in the cluster, the primary online and the replica showing as offline, would you expect the replica to be offline?

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  • george sibbald

    SSC Guru

    Points: 104200

    george sibbald (4/22/2016)


    As I have multi subnets (two) I have two IP addresses for the listener resource in the cluster, the primary online and the replica showing as offline, would you expect the replica to be offline?

    to answer my own question, yes this is correct, for the replicas the listener shows as offline within failover cluster manager

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  • Brandie Tarvin

    SSC Guru

    Points: 172517

    Perry Whittle (3/25/2015)


    I have not covered backups in detail as there will be varying preferences involved. I may do something post the stairway series.

    Quick question on the backups... Does Always On take its own backups? Or does it rely on the backups I am setting up through other means?

    I'm worried about chain breakage and whether or not the recovery/backup solution I am designing will be interfered with by Always On, or if I can just point it to my pre-existing backup location and have it use those backups.

    Following that thought... I can't seem to find much information on what the Always On backup types actually mean. The way your article phrases it, it sounds as if Always On will be doing its own backups. So if I choose Prefer Secondary, the secondary instance will be getting its databases backed up but the primary instance won't, which if I have these two in Asynch mode, might miss some data in case of failure. Could you clarify?

    Brandie Tarvin, MCITP Database AdministratorLiveJournal Blog: http://brandietarvin.livejournal.com/[/url]On LinkedIn!, Google+, and Twitter.Freelance Writer: ShadowrunLatchkeys: Nevermore, Latchkeys: The Bootleg War, and Latchkeys: Roscoes in the Night are now available on Nook and Kindle.

  • Brandie Tarvin

    SSC Guru

    Points: 172517

    And now a question about the Listener... I need an IP address and a Network name, I'm assuming this is a DNS record of A Name type? Or do I need to get a C Name record for the network name?

    If I'm reading this correctly, an AG with 3 secondary replicas only needs 1 IP / Network name, not an IP for each replica... Yes / No / Maybe?

    EDIT: Except looking at George's comments, maybe I need two IPs / Network names? I have a 4 node cluster, two nodes on Data Center A and two nodes on Data Center B. DC-A will have synchronous replicas between them and then both asynch to DC-B. Both DCs are on different subnets.

    I just want to be sure I understand this before I order these items from our DNS admin.

    BTW, beautifully written articles, Perry. Very detailed.

    Brandie Tarvin, MCITP Database AdministratorLiveJournal Blog: http://brandietarvin.livejournal.com/[/url]On LinkedIn!, Google+, and Twitter.Freelance Writer: ShadowrunLatchkeys: Nevermore, Latchkeys: The Bootleg War, and Latchkeys: Roscoes in the Night are now available on Nook and Kindle.

  • Brandie Tarvin

    SSC Guru

    Points: 172517

    Another question. Does Always On require a quorum drive?

    Windows 2012 (clustered) can do with or without a quorum drive. But you mention quorum in your article so much, I wanted to verify whether or not you knew if it was a requirement of AG.

    Brandie Tarvin, MCITP Database AdministratorLiveJournal Blog: http://brandietarvin.livejournal.com/[/url]On LinkedIn!, Google+, and Twitter.Freelance Writer: ShadowrunLatchkeys: Nevermore, Latchkeys: The Bootleg War, and Latchkeys: Roscoes in the Night are now available on Nook and Kindle.

  • george sibbald

    SSC Guru

    Points: 104200

    Brandie Tarvin (6/22/2016)


    Perry Whittle (3/25/2015)


    I have not covered backups in detail as there will be varying preferences involved. I may do something post the stairway series.

    Quick question on the backups... Does Always On take its own backups? Or does it rely on the backups I am setting up through other means?

    no, AG does not take its own backups, you have to set those up in whatever is the normal way for you. If you will be using a listener and have automatic failover you may have to automate checking which node is performing your backups and enable\disable backup jobs. We use Olla's scripts on our AGs which recognise the role the node is playing and acts accordingly, which is very nice.

    if I choose Prefer Secondary, the secondary instance will be getting its databases backed up but the primary instance won't, which if I have these two in Asynch mode, might miss some data in case of failure. Could you clarify?

    Like any backup it will consistent at the point it was taken on the replica, so there will be no more data loss

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