Understanding Hard Links and Shadow Copies in Large Volume Shadowing
In the world of data protection and backup, two important concepts are Hard Links and Shadow Copies. These concepts are crucial in the implementation of Large Volume Shadowing, a technology used to create and manage shadow copies of a volume in Windows Server systems.
Hard Links
A Hard Link is a link to a file that points directly to the file's data. This means that changes made to the file are reflected in all hard links that point to it. Hard links are useful in situations where multiple users need access to the same file, but each user needs to have their own copy of the file that they can modify without affecting the original file or other users' copies.
Hard links are created using the fsutil hardlink create command in Windows. For example, to create a hard link to a file named example.txt, you would use the following command:
fsutil hardlink create link.txt example.txtThis creates a new file named link.txt that is a hard link to the example.txt file. Both files now point to the same data, so changes made to one file are reflected in the other file.
Shadow Copies
A Shadow Copy is a snapshot of a volume at a specific point in time. Shadow Copies are used to create backups of a volume, and to allow users to restore previous versions of files and folders. Shadow Copies are created using the Volume Shadow Copy Service (VSS) in Windows Server systems.
Shadow Copies are created using the vssadmin create shadow /for= command in Windows. For example, to create a shadow copy of the C: drive, you would use the following command:
vssadmin create shadow /for=C:This creates a new shadow copy of the C: drive that can be used to restore previous versions of files and folders.
Large Volume Shadowing
Large Volume Shadowing (LVS) is a technology used to create and manage shadow copies of a volume in Windows Server systems. LVS allows administrators to create shadow copies of volumes that are larger than 64GB, which is the maximum size that can be handled by the traditional VSS technology.
LVS uses Hard Links to create multiple shadow copies of a volume without consuming additional disk space. This is because each shadow copy is a Hard Link to the original volume, so changes made to the original volume are reflected in all shadow copies. This makes LVS an efficient and effective way to create and manage shadow copies of large volumes.
Example: Creating a Shadow Copy of a Large Volume
To create a shadow copy of a large volume using LVS, you would use the following command:
vssadmin create shadow /for=C: /auto recoverThis creates a new shadow copy of the C: drive using LVS. The /auto recover option is used to enable automatic recovery of the shadow copy in case of a failure.
- Hard Links are links to a file that point directly to the file's data
- Shadow Copies are snapshots of a volume at a specific point in time
- Large Volume Shadowing (LVS) is a technology used to create and manage shadow copies of a volume in Windows Server systems
- LVS uses Hard Links to create multiple shadow copies of a volume without consuming additional disk space