序章
次のガイドは、AWS クラウドの Windows で実行されている SAP ASCS と ERS をクラスター化する方法に関する詳細なステップバイステップガイドです。 この例では、クラスター内に2つのノード（SIOS1、SIOS2）があり、各ノードが同じ AWS リージョン内の異なるアベイラビリティーゾーンに存在することを前提としています。 例に従うときは、コンピュータ名、IP アドレス、およびその他の変数を、ご使用の環境に適用可能なものに置き換えてください。
最初のいくつかのセクションは、Microsoft Cloud MVP の David Bermingham によって書かれた このブログ記事 で詳しく説明されています。 以下の手順に進む前に、ブログ記事を確認することをお勧めします。
このガイドでは、Windows、AWS、および SAP にある程度精通していることを前提としています。
Step 1: プロビジョニングサーバー
インスタンスの種類を選ぶ
インスタンスストアストレージ（エフェメラルディスクとも呼ばれる）が接続されているインスタンスを選ぶことが重要です。このディスクを使用して、後述する DataKeeper のビットマップファイルを保存します。サポートするインスタンスタイプの一覧は 以下 の通りです。
各インスタンスにプライマリーとセカンダリーのアドレスを追加する
各インスタンスへの EBS ボリュームの追加
サーバーをプロビジョニングする際には、各サーバーに少なくとも1つの追加 EBS ボリュームをアタッチしてください。
セキュリティグループの開放
この例では、事前にセキュリティグループを作成し、VPC 内のインスタンス（10.0.0.0/16）間ですべてのトラフィックを自由に流せるようにしています。また、RDP ポートを開放し、各インスタンスに直接リモートアクセスできるようにしました。セキュリティプロトコルを遵守するために、クラウド管理者に相談する事をお勧めします。セキュリティグループに関する追加情報については、AWS のドキュメント を参照してください。
Step 2：各クラスターノードでのサーバーの設定
- 名前を変更し、ドメインに追加する
- Windows ファイアーウォールをオフにする
- IE の拡張セキュリティ設定をオフにする
- Chrome をインストールし、デフォルトブラウザにする
- 各サーバーにソフトウェアをダウンロードする
- SAP をインストール
- DataKeeper ソフトウェアとライセンスを入れる
- Vcredist_x64
- 各クラスターノードに vcredist_x64 をインストールする
- ASCS と ERS のバーチャルネームに対して DNS の A レコードを作成します。この例では、以下のレコードを作成します。
SAPASCS 10.0.2.152
SAPERS 10.0.2.153
Step 3：Windows Server Failover Clusterの作成
フェイルオーバークラスタリング機能を有効にする
各クラスターノードで以下の Powershell スクリプトを実行します。
Install-WindowsFeature -Name Failover-Clustering -IncludeManagementTools
クラスター検証の実行
いずれかのノードで以下のコマンドを実行し、クラスタの検証を行います。
Test-Cluster -Node sios1,sios2
検証レポートでは、ネットワークインターフェースが 1 つであることや、共有ストレージがないことなどの警告が表示されます。これらの警告は、AWS で実行されている SANless クラスターで予期されるものであるため、無視できます。
クラスターを作成する
AWS でクラスターを作成する場合、WSFC のインターフェースではなく PowerShell で行うことが重要です。クラスターを作成する際には 前のステップ でインターフェースに追加したセカンダリー IP アドレスのうち、2つを使用することになります。
クラスターノードの1つで、以下の PowerShell コマンドを実行します。
New-Cluster -Name sapcluster -Node sios1,sios2 -StaticAddress 10.0.2.151, 10.0.3.151 -NoStorage
ファイル共有監視の追加
まず、3rd アベイラビリティゾーンにある別のサーバーにフォルダを作成します。フォルダを作成したらそれを共有し、クラスター名オブジェクト（CNO）に共有レベルでの変更権限とセキュリティレベルでの変更権限を与えます。
パーミッションが割り当てられたら、以下の PowerShell コマンドを実行してクラスタークォーラムを更新し、このファイル共有監視を追加します。
Set-ClusterQuorum -FileShareWitness \\dc1\Sapcluster
Step 4：EBSボリュームのフォーマット
Earlier we added additional EBS volumes to each cluster node. The nodes also have an ephemeral drive attached to them. The volumes can be initialized either MBR or GPT.
Initialize the Disk
Format the Volumes
Once they are initialized, format each volume NTFS and assign them drive letters.
Configure EC2launch
The ephemeral drive will be used to hold the DataKeeper bitmap file. It is important to ensure that the ephemeral drive is mounted each time the server starts up. Configure EC2Launch to ensure this process is automated.
Step 5：ページファイルの調整
Windows in AWS has automatic pagefile memory management enabled by default. We want to disable that and at the same time increase the default size of the pagefile to meet the requirements of SAP. SAP recommends a minimum size of 20480 MB.
Step 6: DataKeeper のインストール
We are now ready to install DataKeeper. As part of the installation, you will be asked to specify a service account. The only requirement is that the account must be a member of the Local Administrators group on each of the cluster nodes. Create that account and add it to the local Administrators group on each node before you continue with the installation.
Run the DataKeeper setup on each node and accept the default options as shown below.
Step：7 インテントログの再配置 (ビットマップファイル)
For optimal performance, you must relocate the bitmap file to the local ephemeral storage, aka local instance store volume. Please refer to the SIOS documentation for instructions on relocating the bitmap file.
Step：8 DataKeeper の設定
It is now time to use DataKeeper to replicate the EBS volume(s) between each of the cluster nodes and to register the DataKeeper Volume Resource(s) in the cluster’s Available Storage. The steps below only need to be run on one of the cluster nodes.
Connect to Server
Use the DataKeeper interface to connect to each of the cluster nodes. DataKeeper can be run from either of the cluster nodes.
Once you connect, your Server Overview report should look something like this:
Create DataKeeper Job
You are now ready to replicate your volumes. Click on Create Job and follow the screenshots below.
Register DataKeeper Volume in Available Storage
The last step of the Job Creation process asks if you want to register the volume in Windows Server Failover Clustering (WSFC). Click Yes.
Open the WSFC Manager and you will now see the DataKeeper Volume resource in Available Storage.
Step：9 SAP High-Availability System のインストール
First Cluster Node Installation
Before starting the SAP Installation, make sure you have created a DNS Type A record for SAP Virtual Instance Host on the DNS Server as we described in an earlier step.
You will perform a regular SAP Windows Cluster installation. For more information regarding SAP installation on Microsoft Windows Failover Cluster, please refer to official SAP documentation here.
Current Host Server
Before you begin, make sure the primary server is the Current Host Server.
Grant the Cluster Name Object (CNO) Permissions on the OU
In order to avoid possible security issues with creating the cluster objects in the next steps, it is advisable to grant the CNO permissions on the OU that contain the computer objects. This can be done on one of the domain controllers by a domain admin.
Run SAPINST
In the next steps, we will install the ASCS/ERS cluster on the first cluster node. Follow along with the screenshots below.
Log on as Domain Admin user at the first Windows Cluster instance and run the SAP Installation through sapinst.
Click Next.
The computer will log off at this point. Log back on to continue the installation.
It may take a few moments before the next screen appears.
The SAP System ID is just three letters that identify this system. The Network Name for ASCS and ERS are the same as the names we entered in DNS in an earlier step. The DataKeeper Volume D is the DataKeeper Volume Resource we created earlier.
Specify the folder where you have downloaded the SAP software.
Click Next and it will find your package location.
Click Next to continue.
Notice at this point there are two cluster resource groups with related resources being created in WSFC.
Step 10: 2台目のクラスターノードのインストール
The first cluster node installation was completed without too much effort. In a normal cluster where all the cluster nodes reside in the same subnet, the installation of the second cluster node would run just as smoothly. However, because this is AWS and the nodes reside in different subnets, there are some steps needed to address the unique requirements of a multi-subnet cluster.
Update DNS
Before we proceed, we have to fix the A records we created earlier. It was necessary to create those A records so that the first SAP node could be created properly. However, you will see that those A records in DNS are “static”. Static records cannot be updated by WSFC, which is necessary in a multi-subnet cluster.
Delete the A records from DNS so that the WSFC Manager can re-register them as dynamic records. Right-click on each of the two A records we created earlier and delete them.
In the WSFC Manager, bring the two name resources offline in each of the two cluster groups and then bring the resources back online. This process will re-register the two A records in DNS. This time they will be dynamic records.
Refresh your DNS zone and it should now look like this.
Change TTL
By default, the time to live (TTL) on each of those A records is 20 minutes. That is much too long for a client to wait after a failover to receive the new IP address. Instead, we are going to adjust the TTL to 15 seconds.
To adjust the TTL on a cluster name resource, run the following PowerShell command once for each name resource. This command can be run from either cluster node.
Get-ClusterResource -Name “SAP DAB ERS NetName” | Set-ClusterParameter -Name HostRecordTTL -Value 15
Get-ClusterResource -Name “SAP DAB NetName” | Set-ClusterParameter -Name HostRecordTTL -Value 15
Change RegisterAllProvidersIP
A multi-subnet cluster can handle client redirection a few ways. It’s beyond the scope of this article to discuss the differences. To handle SAP client redirection we need to ensure the RegisterAllProvidersIP property of each cluster name resource is set to 0. Run the following PowerShell command on each cluster node.
Get-ClusterResource -Name “SAP DAB ERS NetName” | Set-ClusterParameter RegisterAllProvidersIP 0
Get-ClusterResource -Name “SAP DAB NetName” | Set-ClusterParameter RegisterAllProvidersIP 0
It is important to bring both of the cluster resource offline and online again to ensure that the changes made in the last two sections are applied.
Add IP Address Resource to Support Multi-Subnet Cluster
When configuring clusters for applications like SQL Server, the installer recognizes when the cluster is a multi-subnet cluster. However, the SAP installer does NOT recognize that fact, so we need to perform some of the configuration steps manually. One of those steps is to create the cluster IP address resources that reside in the subnet of the secondary node. The steps are as follows:
- Create the IP Resources
- Assign the IP Address
- Create the “Or” Dependency
Follow the screenshots below to complete these steps on one of the cluster nodes for each of the two cluster resource groups.
Add a new IP address.
Configure the IP address so it is associated with the Network of the secondary node. Give it one of the unused secondary addresses configured earlier.
Make the server name resource dependent on this additional IP address using the “OR” functionality.
Complete the same process for the other server name resource as shown below.
It is normal for these addresses to be offline. They will only be online if the cluster workload is running in that subnet.
Change Cluster Resource Restart Policy
On occasion, the SAP ASCS Service will fail to start upon a switchover or failover. The reason this most often happens is that the service is dependent upon the clustered file share to be available. With the TTL set to 15 seconds, we have observed on occasion that the file share is not available before the ASCS service tries to start. When this occurs it fails to come online. Simply bringing the resource online again after the failure usually fixes the issue. However, that requires user intervention and defeats the purpose of failover clustering.
The fix to this problem is to adjust the Maximum restarts and Delay between restarts properties of the ASCS Service resource to give the ASCS service a little time to come online if the file server resource IP is not yet available. The settings pictured below are some sample settings that should be more than sufficient. If you have a large complex DNS environment, increase these parameters to meet the needs of your environment.
The other parameter that can impact the reconnection is the TTL. We set it to 15 seconds earlier. However, if you have a large AD environment that takes time to update the DNS zones, you may need to decrease the TTL even further and/or allow more restart attempts and increase the delay between restarts.
For good measure, it is recommended to do the same for your SAP Instance Resource.
Adjust Permissions on the USR Folder
Add permissions for the person who is doing the install to the USR folder that was created on the replicated volume. The folder will be on the D drive (or whatever replicated volume you used).
From the secondary node, confirm that you can see the file share that was created using the server name resource.
Run the SAPINST on the Second Node
Follow the screenshots below to complete the installation of the additional cluster nodes.
If the above screen seems to hang here for a while, click on the message and the installation should to start progressing again.
The next step will timeout and fail after 5 minutes.
The process of installing the second moved all the resources to the second node.
To get the installer to complete after the Error and the installer times out, you may need to move both of the cluster resources back to the primary node and click on Retry to complete the installation.
Once both cluster roles are back in service on the primary node, click the Retry button on the SAPinstaller. The installation will then be completed as shown below.
Step 11: Primary Application Server and Additional Application Server Installation
For more information regarding SAP installation on Windows, including the Primary Application Server and Additional Application Server, refer to official SAP documentation here.
After installing the PAS and AAS, you must deactivate the internal cache for hostnames and services names. For more information please refer to SAP note 1425520 – Disable NI cache for host and service names.
Conclusion
In this Step by Step guide, we have shown how to configure SIOS DataKeeper and integrate with Windows Failover Clustering for ABAP SAP Central Services and Enqueue Replication Server.
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