Tuesday, March 14, 2006
Good cluster configuration...
I just remembered a conversation I had with a mate of mine, he stated that the only good cluster configuration is Inactive/Passive... Go figure.... :)
Monday, March 13, 2006
The fast recovery components
The fast recovery components
Creation of Shadow Copies
As I stated earlier, the process of creation initiates by the requestor (a backup program) contacting the Volume Shadow Copy Service (VSC service) to request a copy of the System State. The VSC service will act as a coordinator and notifies the System State writers to prepare for writing data for creation of a shadow copy.
Once the data is ready for the actual backup process each writer notifies the VSC service which then relays information to the backup requestor. Next step is that the requestor halts Active Directory I/O writes as long as it takes the provider to create single point-in-time copies of the three volumes. Usually this takes just a few seconds and should have no to little impact on Active Directory operations.
After the copy is made the VSC service will be instructed to break the connection with the original and the copy. At this point the shadow copy becomes read-only and the original will continue as usual (read/write). Now we are at the point where the shadow copy is no longer associated with a particular server and resides on the SAN until we need it.
Creation of Shadow Copies
As I stated earlier, the process of creation initiates by the requestor (a backup program) contacting the Volume Shadow Copy Service (VSC service) to request a copy of the System State. The VSC service will act as a coordinator and notifies the System State writers to prepare for writing data for creation of a shadow copy.
Once the data is ready for the actual backup process each writer notifies the VSC service which then relays information to the backup requestor. Next step is that the requestor halts Active Directory I/O writes as long as it takes the provider to create single point-in-time copies of the three volumes. Usually this takes just a few seconds and should have no to little impact on Active Directory operations.
After the copy is made the VSC service will be instructed to break the connection with the original and the copy. At this point the shadow copy becomes read-only and the original will continue as usual (read/write). Now we are at the point where the shadow copy is no longer associated with a particular server and resides on the SAN until we need it.
Using EFS on virtual DCs
I just read this post about the possibility to use EFS to encrypt a DC that is running as a virtual machine. Sounds interesting, need to spend some time in the lab :)
Thursday, March 09, 2006
When do you need to recover AD?
...hopefully never!
But just in case, I will describe something called Fast Recovery during the following days...
There are alternatives to tape backups such as lag sites, but I will not go into that but rather I will talk about how it is possible to use shadow copies instead. I find it interesting and in conjunction with tape backups it can be effective.
The reason way I found this interesting is because it is fast and use a mirroring process that doesn't affect the system performance much. So in order to understand this we need some information how the underlying services works. Not to get into bit-level discussion I will give an overview:
Volume Shadow Copy (I will call it VSC)
With VSC you can create point-in-time snapshots of a volume, the service itself coordinates with other applications like backup software for instance and storage hardware to enable app-aware data management and it also support backup of open files.
There are three components that are needed in order to make a full shadow copy:
1. Requestor, which is the utility that request the copy (or rather request for the creation)
2. Writer, this is the software (app-specific) that makes sure that the data is ready to be copied.
3. Provider, this component gives the functionality to make the copy. VSC can use 3rd party hardware provider if needed.
Virtual Disk Service (I will call it VDS)
To make it short, it provides volume management with a single Windows interface which is used to manage storage devices. It also provides APIs for ISVs and IHVs to create storage solutions. The service itself use two CLI utilities, Diskpart and Diskraid. The Diskpart command is used to control creation, deletion and extension of dynamic and basic disk partitions. Diskraid is used to configure hardware RAID, to be specific, it is used to create, extend, delete and unmask LUs (logical units) on SANs.
Well, it simply makes your VSC data available for use. It do this by unmasking the backups stored on SAN. This means that it makes them visible and change the status from read-only to read/write. It also mounts the volume on the server. The whole process is called transport and is a virtual process since the data is on the storage array.
That is all I have time for now, got to catch a flight. I will continue another day :)
But just in case, I will describe something called Fast Recovery during the following days...
There are alternatives to tape backups such as lag sites, but I will not go into that but rather I will talk about how it is possible to use shadow copies instead. I find it interesting and in conjunction with tape backups it can be effective.
The reason way I found this interesting is because it is fast and use a mirroring process that doesn't affect the system performance much. So in order to understand this we need some information how the underlying services works. Not to get into bit-level discussion I will give an overview:
Volume Shadow Copy (I will call it VSC)
With VSC you can create point-in-time snapshots of a volume, the service itself coordinates with other applications like backup software for instance and storage hardware to enable app-aware data management and it also support backup of open files.
There are three components that are needed in order to make a full shadow copy:
1. Requestor, which is the utility that request the copy (or rather request for the creation)
2. Writer, this is the software (app-specific) that makes sure that the data is ready to be copied.
3. Provider, this component gives the functionality to make the copy. VSC can use 3rd party hardware provider if needed.
Virtual Disk Service (I will call it VDS)
To make it short, it provides volume management with a single Windows interface which is used to manage storage devices. It also provides APIs for ISVs and IHVs to create storage solutions. The service itself use two CLI utilities, Diskpart and Diskraid. The Diskpart command is used to control creation, deletion and extension of dynamic and basic disk partitions. Diskraid is used to configure hardware RAID, to be specific, it is used to create, extend, delete and unmask LUs (logical units) on SANs.
Well, it simply makes your VSC data available for use. It do this by unmasking the backups stored on SAN. This means that it makes them visible and change the status from read-only to read/write. It also mounts the volume on the server. The whole process is called transport and is a virtual process since the data is on the storage array.
That is all I have time for now, got to catch a flight. I will continue another day :)
Windows Server 2003 Disaster Recovery
As many of you already know, besides the project in Finland I also do a tour (ExpertZone) in Sweden. One of the sessions is about troubleshooting AD and I get a lot of questions about recovery and the different ways of doing it.
Most people tend to have similar questions so I will start a series of posts about this topic, so keep an eye on this blog if you're interested in disaster recovery :)
Most people tend to have similar questions so I will start a series of posts about this topic, so keep an eye on this blog if you're interested in disaster recovery :)
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