The work of creating these shadow copies is done in software.Ī software-based shadow copy provider must maintain a “point-in-time” view of a volume by having access to a data set that can be used to recreate volume status prior to the shadow copy. These providers are implemented as a user-mode DLL component and at least one kernel-mode device driver, typically a storage filter driver.
Software-based shadow copy providers typically intercept and process I/O requests in a software layer between the file system and the volume manager software. The requestor also communicates with the writers to gather information about what should be backed up and how it should be backed up. Requestors can also be management applications that manage shadow copy creation and usage, or fast recovery solutions which are specific products that reduce service level agreement (SLA) times for specific applications. The Volume Shadow Copy Service is invoked by the requestor, which is typically a backup application that creates shadow copy volumes to back up data while the source volume continues to operate in production. Requestors: Initiating Shadow Copy Creation
Note that when I run “vssadmin list providers” on my Windows Vista Business SP1 system, it explicitly reports the existence of the StorageCraft VSS provider: You can verify this by installing these three products and then typing the command: C:\> vssadmin list providers You will see Microsoft's system provider "volsnap" as well as StorageCraft's VSS software provider.
Neither Symantec's nor Acronis' device driver is a VSS software provider.
VSS-aware snapshot device drivers which provide snapshots of volumes to backup software are called "VSS Software Providers" and of the three products only StorageCraft's snapshot device driver is a true VSS Software Provider. StorageCraft and Acronis allow you to backup your Exchange server without taking it down. Symantec's online knowledge base indicates that you must take down your Exchange server in order to successfully backup its data. Interacting properly with VSS is critical to performing a good quality backup and if you are an enterprise customer you really need to give this particular issue some weight. This will cause these applications to perform a quick flush of their critical data, without interrupting anything, so that the snapshot device driver will capture their data in its optimal state. When a backup product requests a backup, it can tell VSS to "quiesce" these VSS-aware applications. This service can be used by backup products (called "VSS Requestors"), as well as by applications (called "VSS writers), which create data (such as Exchange, SQL Server, etc). Microsoft provides a framework called the "Volume Shadow Copy Service" (VSS) to assist in the creation of clean backups. I checked the symsnap.sys file in NG14, and its made by Storagecraft, version 7.7, Copyright 2001-2008.Ĭan someone with NG12 run the "vssadmin list providers" command to see if NG12 has a VSS provider? Also, what is the version of symsnap.sys? Provider name: 'Symantec Software VSS Provider' Vssadmin 1.0 - Volume Shadow Copy Service administrative command-line tool
You can tell NG14 supports it by running the vssadmin command:Ĭ:\Documents and Settings\Woodb000>vssadmin list providers This is arguably the most important factor to consider when looking at hot image backup software. NG14 has licensed updated technology from Storagecraft, and fully supports VSS (volume shadowing).