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Accepted
Scott Chamberlain
Asked: 2011-09-16 10:16:19 +0800 CST

Why does Sql server write 100's of files to System Volume Information (all with the same name)

  • 772

I noticed that SQL Server has a surprisingly large number of writes to \System Volume Information\{guid1}{guid2}

What is Sql Server doing when something like this happens?

enter image description here

In the above image half of my write IO for sqlsevr.exe is used for the System Volume Information writes.

This is being run in Windows 7 Profressional.

here is the output of vssadmin list shadows

vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.

Writer name: 'Task Scheduler Writer'
   Writer Id: {d61d61c8-d73a-4eee-8cdd-f6f9786b7124}
   Writer Instance Id: {1bddd48e-5052-49db-9b07-b96f96727e6b}
   State: [1] Stable
   Last error: No error

Writer name: 'VSS Metadata Store Writer'
   Writer Id: {75dfb225-e2e4-4d39-9ac9-ffaff65ddf06}
   Writer Instance Id: {088e7a7d-09a8-4cc6-a609-ad90e75ddc93}
   State: [1] Stable
   Last error: No error

Writer name: 'Performance Counters Writer'
   Writer Id: {0bada1de-01a9-4625-8278-69e735f39dd2}
   Writer Instance Id: {f0086dda-9efc-47c5-8eb6-a944c3d09381}
   State: [1] Stable
   Last error: No error

Writer name: 'ASR Writer'
   Writer Id: {be000cbe-11fe-4426-9c58-531aa6355fc4}
   Writer Instance Id: {6584bb82-094c-4896-9be2-880ff9fb4d80}
   State: [1] Stable
   Last error: No error

Writer name: 'System Writer'
   Writer Id: {e8132975-6f93-4464-a53e-1050253ae220}
   Writer Instance Id: {669bba38-6066-4bf6-99af-8d312f66648d}
   State: [5] Waiting for completion
   Last error: No error

Writer name: 'SqlServerWriter'
   Writer Id: {a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}
   Writer Instance Id: {48de0d7f-b7a0-457e-8bab-fefe2089286e}
   State: [1] Stable
   Last error: No error

Writer name: 'MSSearch Service Writer'
   Writer Id: {cd3f2362-8bef-46c7-9181-d62844cdc0b2}
   Writer Instance Id: {d5c4ab16-b67e-4476-976b-4dba610084d8}
   State: [5] Waiting for completion
   Last error: No error

Writer name: 'WMI Writer'
   Writer Id: {a6ad56c2-b509-4e6c-bb19-49d8f43532f0}
   Writer Instance Id: {5e334911-6049-4d29-8d33-d9b230b46ec2}
   State: [5] Waiting for completion
   Last error: No error

Writer name: 'COM+ REGDB Writer'
   Writer Id: {542da469-d3e1-473c-9f4f-7847f01fc64f}
   Writer Instance Id: {e9dde2da-5cee-4d65-ac50-45387be4b600}
   State: [1] Stable
   Last error: No error

Writer name: 'Registry Writer'
   Writer Id: {afbab4a2-367d-4d15-a586-71dbb18f8485}
   Writer Instance Id: {9825b95f-94a0-438b-a359-4111aa308a60}
   State: [1] Stable
   Last error: No error

Writer name: 'BITS Writer'
   Writer Id: {4969d978-be47-48b0-b100-f328f07ac1e0}
   Writer Instance Id: {d23d67d3-c421-4e9a-9965-123ec802bfcc}
   State: [1] Stable
   Last error: No error

Here is the output of vssout list shadows (too long to post here)

sql-server-2005

4 Answers

  1. Smells like VSS snapshots.

    Do you have software (probably backups) telling SQL Server to create VSS snaps?

    • 4

  2. My guess is that you're doing a backup of the server itself, or a backup of the SQL Server databases with a VSS aware backup program (Windows Backup, SQL Maintenance Plan or SQL database backup job, or third party VSS aware backup software).

    • 4
  3. Best Answer

    It's Windows doing shadow copies of your E-drive.

    (This is not normal to use on data/log drives for SQL server, it increases I/O tremendously).

    Edit: Or, well.. atleast schedule it to something sane, like one hour before everyone comes to work.

    • 3

  4. You can also disable shadow copy on the folder of your database's files: http://msdn.microsoft.com/en-us/library/aa819132(v=vs.85).aspx

    • 0