今天一上班，就发现有一台服务的每周备份报 156 号错误，形式如下：
STATUS CODE: 156 "snapshot error encountered" occurs when utilizing VSP or VSS for open file backups. -------------------------------------------------------------------------------- Exact Error Message snapshot error encountered (156) Details: Overview: STATUS CODE: 156 "snapshot error encountered" occurs when utilizing VERITAS Volume Snapshot Provider (VSP) or Microsoft Volume Shadow Copy Service (VSS) for a client backup.
查看了一下官方的解释：Windows 平台的 NetBackup 5.0 以上版本的 client 如果报 156 号错误，这和备份 Open File 有关，常常是因为创建“Snapshot”的 VSP/VSS 缓存文件空间不足造成的。
可以在 Client 上查看到相应的 Log，形式如下：
bpbkar
6:00:14.156 AM: [452.976] <2> tar_base::V_vTarMsgW: ERR - Snapshot Error while reading file: Volume{43877774-d2zz-4rar-r5id-fg9i49fuje7815}\Accounts\Akerfeldt\data\Amm.txt
6:00:14.171 AM: [452.976] <2> tar_base::V_vTarMsgW: FTL - Backup operation aborted!
6:00:14.218 AM: [452.976] <2> tar_base::V_vTarMsgW: INF - EXIT STATUS 156: snapshot error encountered
解决办法：
1. 首先确定是否需要备份 Client 上的 Open file 文件，如果不需要可以关闭这个功能。NetBackup 默认是打开这个功能的。
- 如何确认是否以及使用了 VSS 或 VSP 功能
- Within the NetBackup Administration Console, expand Host Properties in the hand pane
- Within Host Properties, click Master Server and then the double-click the name of the Master Server in the right pane
- Click on the Client Attributes section
- If the client in question is listed here, click on the client name. If it is not listed, add and click on the client name.
- Click the Windows Open File Backup tab
- Ensure that Enable Windows Open File Backups for this client is not selected if open file backups are not required
2. 如果需要备份 open file，造成 snapshot error 的一个可能的原因是因为 VSP 或 VSS 的缓存大小设置问题。
如何去配置缓存大小？
- 对于 VSP
- Within the NetBackup Administration Console, expand Host Properties in the left pane
- Within Host Properties, click Clients and then double-click the name of the client in the right pane
- Expand the Windows Client section and click on VSP to display cache settings
Attention!!!
Make sure the Customize the cache sizes check box is not selected. With this not selected, NetBackup automatically determines the best VSP cache file sizes. In most cases, NetBackup will be able to create a large enough VSP cache file for backups if this is not selected.
If errors still occur with this not selected, it is possible to increase the initial VSP cache size and maximum VSP cache size manually. These settings vary depending on the client’s requirements. Use caution when manually specifying sizes for the Initial and Maximum Cache Size, since these settings will be used regardless of volume size.
Refer the NetBackup System Administrator’s Guide for more information on changing the configuration of VSP cache file sizes. If backups still abort with error status 156 after making changes to the VSP cache file size configuration, there may not be enough free disk space on the affected client. Free up as much disk space on the drives of the affected client as possible.
- 对于 Volume Shadow Copy (VSS) (Windows 2003 Only):
- In Windows, right-click My Computer and select Manage
- In the console tree, right-click Shared Folders, select All Tasks, and then Configure Shadow Copies
- Select the volume on which to make changes, and then click the Settings button
- In the Settings dialog box, change the Maximum Size setting to either No Limit or a size large enough to suit the requirements of the installation and usage of VSS