A. VSS writers to ensure data on disk is in a consistent and suitable for backup or restore, and each application has its own VSS writer. Usually, when you install VSS-compatible applications such as Exchange Server or SQL Server, a VSS writer is automatically installed and registered.
To view which VSS Writers are available on a box, run the command
vssadmin list writers
An example is shown below. Notice that you can see the name of the writer along with its state and any known errors.
C:\>vssadmin list writers
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.
Writer name: 'System Writer'
Writer Id: {e8132975-6f93-4464-a53e-1050253ae220}
Writer Instance Id: {5a49f480-8471-4245-b584-60b892654522}
State: [1] Stable
Last error: No error
Writer name: 'ASR Writer'
Writer Id: {be000cbe-11fe-4426-9c58-531aa6355fc4}
Writer Instance Id: {ab25eb99-ae1c-429f-b805-ae93efcfcbc3}
State: [1] Stable
Last error: No error
Writer name: 'WDS VSS Writer'
Writer Id: {82cb5521-68db-4626-83a4-7fc6f88853e9}
Writer Instance Id: {e8c6bae2-5753-4808-8a4a-fc4cec707ff7}
State: [1] Stable
Last error: No error
Writer name: 'Shadow Copy Optimization Writer'
Writer Id: {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f}
Writer Instance Id: {48701a86-6d02-4590-ad8b-5f473b88893b}
State: [1] Stable
Last error: No error
Writer name: 'SMS Writer'
Writer Id: {03ba67dd-dc6d-4729-a038-251f7018463b}
Writer Instance Id: {27b61b08-6977-4a1c-9ea9-3c55a35268b1}
State: [7] Failed
Last error: No error
Writer name: 'IIS Config Writer'
Writer Id: {2a40fd15-dfca-4aa8-a654-1f8c654603f6}
Writer Instance Id: {a7f77c22-c138-4cf6-b1a2-a74c72b02f24}
State: [1] Stable
Last error: No error
Writer name: 'Registry Writer'
Writer Id: {afbab4a2-367d-4d15-a586-71dbb18f8485}
Writer Instance Id: {4293afa6-c7f1-4555-8784-65ee206421e9}
State: [1] Stable
Last error: No error
Writer name: 'COM+ REGDB Writer'
Writer Id: {542da469-d3e1-473c-9f4f-7847f01fc64f}
Writer Instance Id: {733364a9-a23e-45d8-bafb-697e24866bc3}
State: [1] Stable
Last error: No error
Writer name: 'IIS Metabase Writer'
Writer Id: {59b1f0cf-90ef-465f-9609-6ca8b2938366}
Writer Instance Id: {f453691d-a05b-4a06-b398-29ee3b1d78a4}
State: [1] Stable
Last error: No error
Writer name: 'BITS Writer'
Writer Id: {4969d978-be47-48b0-b100-f328f07ac1e0}
Writer Instance Id: {2456c04f-e388-41bb-b133-14580b0a9e03}
State: [1] Stable
Last error: No error
Writer name: 'WMI Writer'
Writer Id: {a6ad56c2-b509-4e6c-bb19-49d8f43532f0}
Writer Instance Id: {0ae7addd-ee9d-4278-b07a-5f66e3725610}
State: [1] Stable
Last error: No error