問題描述︰
您想解決 Volsnap Event 25 事件

Event Type:            Error
Event Source:        VolSnap
Event ID:                25
Description:          The shadow copies of volume D: were deleted because the shadow copy storage could not grow in time.  Consider reducing the IO load on the system or choose a shadow copy storage volume that is not being shadow copied.
Data:
0000: 00000000 00580002 00000000 c0060019
0010: 00000003 00000000 00000003 00000000
0020: 00000000 00000000

c0060019 = ERROR_SEEK The drive cannot locate a specific area or track on the disk.

說明與方法︰
CAUSE
================
以下兩篇 KB 描述當伺服器 I/O 高時,會遺失 Shadow Copy 的問題

925799 Error message when a Windows Server 2003-based computer has a high level of I/O activity: "The shadow copies of volume Volume_Name were aborted because the diff area file could not grow in time"
http://support.microsoft.com/kb/925799

826936 Time-out errors occur in Volume Shadow Copy service writers, and shadow copies are lost during backup and during times when there are high levels of input/output
http://support.microsoft.com/kb/826936

(826936 is replaced by 833167, 833167 is included in Windows Server 2003 SP2)

RESOLUTION
=================
1. 我們建議您先安裝以下 Hotfix 來更新 VOLSNAP 驅動程式
Rollup update for the volsnap.sys driver in Windows Server 2003 http://support.microsoft.com/kb/967551
After 967551 hotfix is installed, you must change the value of the UseTopDownAlloc registry entry to 1 to resolve the Stop code 0x0000006B issue.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VolSnap\UseTopDownAlloc

2. 設定 MinDiffAreaFileSize 機碼
Registry path: HKLM\SYSTEM\CurrentControlSet\Services\VOLSNAP\MinDiffAreaFileSize

Compute a value that is five percent of the smallest shadow copy storage space on any one volume on the system.

Use the following guidelines to set the MinDiffAreaFileSize value:
If you compute a value that is less than or equal to (<=) 600 megabytes (MB), set the MinDiffAreaFileSize value to 600. If you continue to receive event ID 25, incrementally increase the value until the value exceeds 3,000.
If you compute a value that is more than or equal to (>=) 3,000 MB, set the MinDiffAreaFileSize value to 3000.
If you compute a value that is between 600 MB and 3,000 MB, set the value of MinDiffAreaFileSize to the value that you computed.

MinDiffAreaFileSize controls the initial size of the shadow copy storage area for each shadow copy. The MinDiffAreaFileSize registry key uses the REG_DWORD data type.

The MinDiffAreaFileSize registry key specifies the minimum size of the shadow copy storage area. The default size of the shadow copy storage area is 300 MB, and the maximum size is 3 gigabytes (GB). For an accurate setting, specify a value that is a multiple of 300 MB. Otherwise, the next multiple of 300 MB will be used. A value of 300 is equal to 300 MB, and a value of 3,000 is equal to 3 GB.

Shadow copies might not function correctly if the value of the MinDiffAreaFileSize registry key is larger than the maximum size of the shadow copy storage area. Before you change this registry entry, run the vssadmin list shadowstorage command. Make sure that the shadow copy storage area is larger than 300 MB or that the shadow copy storage area is larger than the value that is set in the registry. Also, make sure that you have at least 300 MB of free space on the shadow copy storage volume.

ADDITIONAL CONSIDERATION
=================
As time passes, the allocated space may increase as more data is modified on the original volume. However, when you have high input/output traffic on the original volume, the shadow copy storage area cannot grow fast enough to hold all the copy-on-write changes. This causes deletion of all the shadow copies on the original volume. This problem is more noticeable in domain controller configurations. By default, the disk write cache is disabled in domain controller configurations.

If you continue to receive event ID 25, follow these steps to resolve the issue:
a. Put the shadow copy storage on another volume, even if the volume is located on the same hard disk.
b. Make sure that the volume that causes event ID 25 is not the same volume that contains the paging file. If the volume that causes event ID 25 contains the paging file, consider putting the paging file on another volume.
c. Make sure that the volume that causes event ID 25 is not used as the shadow copy storage for any other volume.

使用 VSSADMIN 指令修改 Storage 位置以及大小
Method 1)
Run "vssadmin resize shadowstorage /for=c: /on=d: /maxsize=2500mb"
This will set Partition D: for Storage area for Partition C: with size limit of 2500mb (This valve will vary according to your requirement)
Method 2)
Run "vssadmin delete shadowStorage /for=C: /on=C:"
Run "vssadmin add shadowstorage /for=C: /on=D: /maxsize=2500mb"