Chapter 12. Finding and Fixing Problems: the pidiag Utility
4.11 Troubleshooting Backups
Subsystem(s) Name Default
Value Min Max Read Description
All <subsysname >_WriteModTi mesToFilePer iod
60 sec 10 900 Startup
only PI internally keeps track of the last modified date of most of the files that it needs to back up. The last modified times for each subsystem are updated every WriteModTimesToFilePeriod. The smaller the period, the more accurate the last modified time is. A complete list of backed up files along with their last modified dates can be listed with the piartool - backup -identify -verbose command. For archives, the last modified date can also be viewed with piartool -al. Note for archive files:
When a value is written to a PI point, the value is not actually written to the archive until the archive cache is flushed. The maximum period between archive flushes is set by the Archive_SecondsBetweenFlush timeout parameter. After the cache is flushed, the last modified time is updated within WriteModTimesToFilePeriod seconds. All <subsysname >_BackupTim eout 1800 sec 30 86400 Periodically when in system backup mode
The maximum number of seconds to remain in system backup mode. This timeout parameter only pertains to the piartool -systembackup command, which is used to take the audit databases offline. The parameter has no effect for VSS backups or non-VSS backups that are started with the piartool -backup command.
4.11 Troubleshooting Backups
4.11.1 Log Messages
The following log files should be examined for errors.
The backup script log. The backup script log is written to the target directory of the backup and the log file has a name of the form pibackup_dd-mmm-yy_hh.mm.ss.txt. An example backup script log file name is pibackup_5-Aug-05_14.16.22.txt.
The PI Message Log. Messages from the PI Backup Subsystem have a message source of pibackup. Backup-related messages from all other subsystems have a message source of pibackup<subsysname>, such as pibackup_piarchss. You can search for all backup related messages in the log by using pibacku* as a text mask for Message Source.
The NT Event Log. From the Application Log, look for messages from “VSS”, “COM+”, and “ntbackup” sources.
The NTBackup.exe log file (VSS Backups only). If there was a problem creating a VSS shadow copy during a backup, the reason for the failure is logged at the
beginning of the NTBackup.exe log file.
If the “Run As” user for the “PI Server Backup” scheduled task is the same as your account, then you can view the NTBackup log from the Tools > Report… menu of NTBackup. Launch NTBackup from a DOS command prompt and choose to run in advanced mode.
If the PI Server Backup scheduled task was run under the system account, you must browse to the NTBackup.exe log file with Windows explorer to the following directory.
C:\Documents and Settings\Default User.WINDOWS\Local
Settings\Application Data\Microsoft\Windows NT\NTBackup\data
If the scheduled task is run under a user name other than the system account, then replace
Default User.Winodows with the specific user name to get the path to which the
NTBackup.exe log file is written.
4.11.2 VSSADMIN
Vssadmin.exe is the Volume Shadow Copy Service administrative command line tool. You can use the tool to view the status of the VSS writers, VSS Providers, and VSS shadow copies on the system.
4.11 - Troubleshooting Backups
VSSADMIN LIST SHADOWS
A shadow copy is created during the freeze event. If a backup is not currently in progress, the output of vssadmin list shadows should look like the following output that was generated on Windows XP.
e:\pi\adm>vssadmin list shadows
vssadmin 1.0 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001 Microsoft Corp. No shadow copies present in the system.
If there were problems create the shadow copy, look for errors in the NTBackup.exe log file and run vssadmin list shadows to check the status of the failed shadow copy.
VSSADMIN LIST PROVIDERS
Windows XP and Windows 2003 server comes with a default VSS provider. The following is sample output generated on Windows XP.
e:\pi\adm>vssadmin list providers
vssadmin 1.0 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001 Microsoft Corp.
Provider name: 'MS Software Shadow Copy provider 1.0' Provider type: System
Provider Id: {b5946137-7b9f-4925-af80-51abd60b20d5} Version: 1.0.0.7
VSSADMIN LIST WRITERS
The following is sample output for the vssadmin list writers command. When a backup is not in progress, the status of all writers should appear as stable. The name of the writer for the PI System is OSISoft PI Writer. The PI Backup Subsystem registers as a VSS writer with this name.
The following is sample output from Windows XP.
e:\pi\adm>vssadmin list writers
vssadmin 1.0 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001 Microsoft Corp. Writer name: 'OSISoft PI Server'
Writer Id: {0fd0891d-b731-4e59-a35d-48f164383155}
Writer Instance Id: {cf8d5ded-e931-4692-91a0-6b3064c756c3} State: [1] Stable
Writer name: 'Microsoft Writer (Bootable State)' Writer Id: {f2436e37-09f5-41af-9b2a-4ca2435dbfd5}
Writer Instance Id: {c89ae65c-9f26-4bd4-8220-db66757defc7} State: [1] Stable
Writer name: 'MSDEWriter'
Writer Id: {f8544ac1-0611-4fa5-b04b-f7ee00b03277}
Writer Instance Id: {190c16a5-d378-43d6-bdb5-712983abea2b} State: [1] Stable
Writer name: 'WMI Writer'
Writer Id: {a6ad56c2-b509-4e6c-bb19-49d8f43532f0}
Writer Instance Id: {26a1f92f-779d-45d1-900a-21b8af6f0590} State: [1] Stable
Writer name: 'Microsoft Writer (Service State)' Writer Id: {e38c2e3c-d4fb-4f4d-9550-fcafda8aae9a}
Writer Instance Id: {f8dd1e16-4e36-4ed2-9a53-ea4e05bacdb6} State: [1] Stable