Posts Tagged ‘instance’

vRealize Automation Disaster Recovery

January 14, 2018

Introduction

VMware has invested a lot of time and effort in vRealize Automation high availability. For medium and large deployment scenarios VMware recommends using a load balancer (Citrix, F5, NSX) to distribute traffic between vRA appliance and infrastructure components, as well as database clustering (such as MS SQL availability groups) for database high availability. Additionally, in vRA 7.3 VMware added support for automatic failover of vRA appliance’s embedded PostgreSQL database, which was a manual process prior to that.

There is a clear distinction, however, between high availability and disaster recovery. Generally speaking, HA covers redundancy within the site and is not intended to protect from full site failure. Site Recovery Manager (or another replication product) is required to protect vRA in a DR scenario, which is described in more detail in the following document:

In my opinion, there are two important aspects that are missing from the aforementioned document, which I want to cover in this blog post: restoring VM UUIDs and changing vRA IP address. I will cover them in the order that these tasks would usually be performed if you were to fail over vRA to DR:

  1. Exporting VM UUIDs
  2. Changing IP addresses
  3. Importing VM UUIDs

I will also only touch on how to change VM reservations. Which is also an important step, but very well covered in VMware documentation already.

Note: this blog post does not provide configuration guidelines for VM replication software, such as Site Recovery Manager, Zerto or RecoverPoint and is focused only on DR aspects related to vRA itself. Refer to official documentation of corresponding products to determine how to set up VM replication to your disaster recovery site.

Exporting VM UUIDs

VMware uses two UUIDs to identify a VM. BIOS UUID (uuid.bios in .vmx file) was the original VM identifier implemented to identify a VM and is derived from the hardware VM is provisioned on. But it’s not unique. If VM is cloned, the clone will have the same BIOS UUID. So the second identifier was introduced called Instance UUID (vc.uuid in .vmx file), which is generated by vCenter and is unique within a single vCenter (two VMs in different vCenters can have the same Instance UUID).

When VMs are failed over, Instance UUIDs change. Compare VirtualMachine.Admin.AgentID (Instance UUID) and VirtualMachine.Admin.UUID (BIOS UUID) on original and failed over VMs.

Why does this matter? Because vRA uses Instance UUIDs to keep track of managed VMs.  If Instance UUIDs change, vRA will show the corresponding VMs as missing under Infrastructure > Managed Machines. And you won’t be able to manage them.

So it’s important to export VM Instance UUIDs before failover, which can then be used to restore the original values. This is how you can get the Instance UUID of a given VM using PowerCLI:

> (Get-VM vm_name).extensiondata.config.InstanceUUID

Here, on my GitHub page, you can find a script that I have put together to export Instance UUIDs of all VMs in CSV format.

Changing IP addresses

Once you’ve saved the Instance UUIDs, you can move on to failover. vRA components should be started in the following order:

  1. MS SQL database
  2. vRA appliance
  3. IaaS server

If network subnets, that all components are connected to, are stretched between two sites, when VMs are brought up at DR, there are no additional reconfiguration required. But usually it’s not the case and servers need to be re-IP’ed. IaaS server network setting are changed the same as on any other Windows server machine.

vRealize Appliance network settings are changed in vRA appliance management interface, that can be accessed at https://vra-appliance-hostname:5480, under Network > Address tab. The problem is, if IP addresses change at DR, it will be challenging to reach vRA appliance over the network. To work around that, connect to vRA VM console and run the following script from CLI to change appliance’s network settings:

# /opt/vmware/share/vami/vami_config_net

Don’t forget to update the DNS record for vRA appliance in DNS. For IaaS server it’s not needed, as long as you allow Dynamic DNS (DDNS) updates.

Importing VM UUIDs

After the failover all of your VMs will have missing status in vRA. To make vRA recognize failed over VMs you will need to revert Instance UUIDs back to the original values. In PowerCLI this can be done in the following way:

> $spec = New-Object VMware.Vim.VirtualMachineConfigSpec
> $spec.instanceUuid = ’52da9b14-0060-dc51-4733-3b01e912edd2′
> $vm = Get-VM -Name vm_name
> $vm.Extensiondata.ReconfigVM_Task($spec)

I’ve written another script, that will perform this task for you, which you can find on my GitHub page.

You will need two files to make the script work. The vm_vc_uuids.csv file you generated before, with the list of original VM Instance UUIDs. As well as the list of missing VMs in CSV format, that you can export from vRA after the failover on the Infrastructure > Managed Machines page:

This is an example of the script command line options and the output:

You will need to run an inventory data collection from the Infrastructure > Compute Resources > Compute Resources page. vRA will discover VMs and update their status to “On”.

Updating reservations

If you try to run any Day 2 operation on a VM with the old reservation in place, you will get an error similar to this:

Error processing [Shutdown], error details:
Error getting property ‘runtime.powerState’ from managed object (null)
Inner Exception: Object reference not set to an instance of an object.

To manually update VM reservation, on Infrastructure > Managed Machines page hover over the VM and select Change Reservation:

This process is obviously not scalable, as it can take hours, if you have hundreds of VMs. VMware offers an alternative solution that lets you update all VMs by using Bulk Import feature available from Infrastructure > Administration > Bulk Imports. The idea is that you can export all VM configuration details in a CSV file, update compute and storage reservation columns and import back to vRA. vRealize Suite 7.0 Disaster Recovery by Using Site Recovery Manager 6.1 gives very detailed instruction on how to do that in “Bulk Import, Update, or Migrate Virtual Machines” section.

Conclusion

I hope this blog post helped to cover some gaps in VMware documentation. If you have any questions or comments, as always, feel free to leave them in the comments sections below.

References

AWS Cloud Protection Manager Part 3: Backup and Restore

August 21, 2017

Backup

Backups are created according to the schedule specified in the backup policy. We discussed how to configure backup policies in the previous blog post of the series. The list of backups you see on the Backup Monitor tab are your restore points. Backups that are older then the specified retention policy will be purged from the list and you will not see them there, unless you move them to “Freezer”.

It is important to understand that apart from volume snapshots, for each backed up instance CPM also creates an AMI. Those who has hands-on experience with AWS may already know, that AMIs is the only way to create clones of Windows EC2 instances in AWS. If you go to AWS console and try to find a clone action under the instance Action menu, you won’t find any. You will have “Create Image” instead. It creates an AMI, from which you can then spin up a clone of an instance the image was created from.

CPM does exactly that. For each backup policy the instance is under, it creates one AMI. In our example we have four backup policies, that will result in four AMIs for each of the instances. Every AMI has to have at least one storage volume. So CPM will include the root volume of each instance into AMI, just because it has to. But AMIs are required only to restore EC2 instance configuration. Data is restored from volume snapshots, that can be used to create new volumes from them and then attach them to the instance. You can click on the View button under Snapshots to find the corresponding snapshot and AMI IDs.

There is a backup log for each job run as well that is helpful for issue troubleshooting.

Restore

To perform a restore click on the Recover button next to the backup job and you will get the list of the instances you can recover. CPM offers you three options: instance recovery, volume recovery and file recovery. Let’s go back to front.

File recovery is probably the most used recovery option. As it lets you restore individual files. When you click on the “Explore” button, CPM creates new volumes from the snapshots you are restoring from and mount them to the CPM instance. You are then presented with a simple file system browser where you can find the file and click on the green down arrow icon in Download column to save the file to your computer.

If you click on “Volume Only”, you can restore particular volumes. Restored volumes are not attached to any instance, unless you specify it under “Attach to Instance” column. You can then select under “Attach Behaviour” what CPM should do if such volume is already attached to the instance or if you want to automatically detach the original volume, but the instance is running (you can do it only if instance is stopped).

And the last option is “Instance”. It will create a clone of the original instance using the pre-generated AMI and volume snapshots, as we discussed in the Backup section of this blog post. You can specify many options under Advanced Options section, including recovery to another VPC or different availability zone. If anything, make sure you specify a new IP address for the instance, otherwise you’ll have a conflict and your restore will fail. Ideally you should also shut down the original EC2 instance before spinning up a restore clone.

Advanced Features

There are quite a few worth mentioning. So far we have looked at simple EC2 instance restore. But you don’t have to backup whole instances, you can also backup individual volumes. On top of that, CPM supports RDS database, Aurora and Redshift cluster backups.

If you run MS Exchange, Sharepoint or SQL on your EC2 instances, you can install CPM backup agent on them to ensure you have application-consistent backups via VSS, as opposed to crash-consistent backups you get if agent is not used. If you install the agent, you can also run a script on the instance before and after the backup is taken.

Last but not least is DR. Restoring to another availability zone within the region is already supported on instance recovery level. You can choose availability zone you want to restore to. It is not possible to recover to another region, though. Because AWS snapshots and AMIs are local to the region they are created in. If you want to be able to recover to another region, you can configure DR in CPM, which will utilise AWS AMI and snapshot copy functionality to copy backups to another region at configured frequency.

Conclusion

Overall, I found Cloud Protection Manager very easy to install, configure and use. If you come from infrastructure background, at first glance CPM may look to you like a very basic tool, compared to such feature-rich solutions like Veeam or Commvault. But that feeling is misleading. CPM is simple, because AWS simple. All infrastructure complexity is hidden under the covers. As a result, all AWS backup tools need to do is create snapshots and CPM does it well.

General view of IBM DB2 architecture

December 16, 2011

No one would argue that DB2 is one of the leading (R)DBMS products in the market. As any other powerful software product it has complex architecture. Here I’d like to introduce some basic terminology of it in series of posts because sometimes this terminology can become somewhat vague.

Lets kick off by explaining some general view of DB2. Each IBM DB2 installation has following basic levels of architecture:

  • Instance can be understood as a completely independent environment with it’s own security configuration, resource allocation and contains databases and partitions isolated from all other instances. Each instance has its own system processes which manage data. Instance may contain several databases.
  • Database is a most familiar term. It’s a logical unit which holds your data. It has complicated structure which we will explain later on. Database can reside in one or more partitions.
  • Partitions (or nodes) is a way of creating DB2 database cluster for the sake of higher performance. You can split your database onto several servers where each of them will have their own chunk of data. Since more servers means more CPU cores, memory and disk I/O it’s a natural way of scaling DB2. Particular storage resource is called Container.
  • Database is then mapped onto several Tablespaces. Tablespace allows you to manage how database tables are held on your storage resources. For example you can hold your data in files as well as on raw hard drives (which is faster). In addition it’s possible to put frequently used data on SAS hard drives and rarely used on SATA by means of creating two different tablespaces. On top of that you can set up a different page size for each of your tablespaces.

Here is the basic idea of what DB2 represents from the view of systems administrator. To better understand a folding of different levels please refer to this well-known among dbtwoers picture: link.