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Understanding GRT Backup and Restore functionality in Symantec Backup Exec

Created: 08 May 2010 • 2 comments
Dev T's picture
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The simplest way to understand the granular restore functionality is to go through a simple step-by-step description of the way this works in each case. The primary differences to take note of are the differences between the backup-to-disk method and the backup-to-tape method.

Backup to Disk of an Exchange Information Store database with GRT enabled goes through the following steps:

1. GRT backup requests backup data from Exchange server
2. BE Media Server Creates IMG folders in B2d location
3. Data is sent from Exchange server to BE Media Server (unless local)
4. Media Server also requests current ESE.dll version from Exchange Server and writes this to the IMG folder
5. Finally, a test is run against the database using the VFF (virtual file filter EDBProv.dll)
6. The VFF uses ESE.dll to read the Exchange database to make sure it is consistent and that we can recover data from it
7. Backup reports successful (or failed if error conditions are encountered)

Restore from Backup to Disk of Exchange granular mailbox, or public folder, data with GRT enabled:

1. Restore selection data is generated dynamically from IMG backup of Exchange database
2. BE uses the VFF with ESE to generate restore selections
3. VFF puts hard links to .edb and .stm files in vdb_date_xxxx folder
4. Restore job extracts data from IMG folders using VFF/ESE and feeds this to RAWS on Exchange Server
5. RAWS on Exchange Server uses MAPI to write data back to the Exchange database much as if it were from a legacy type backup

Backup to Tape of an Exchange Information Store database with GRT enabled goes through the following steps:

1. GRT backup requests backup data from Exchange server
2. Data is sent from Exchange server to BE Media Server (unless local)
3. BE job engine writes Exchange data to tape in same IMG folder format used to disk
4. Media Server also requests current ESE.dll version from Exchange Server and writes this to the IMG folder on tape
5. MAPI is initialized on the Exchange server by RAWS to gather granular restore data
6. Granular restore data gathered from MAPI session on the Exchange server is written to catalog
7. Granular Catalog data is retained on disk and written to tape
8. Backup reports successful (or failed if error conditions are encountered)

Restore from Backup to Tape of Exchange granular mailbox, or public folder, data with GRT enabled:

1. Restore selection data is provided by catalog data gathered at the end of the backup by MAPI on Exchange server
2. User selects granular mailbox data ONLY (NO Public Folder Granular data is available) to restore
3. Entire set data (all IMG folder data) for that Exchange IS backup job is written to staging area on disk location specified by user
4. Restore job extracts data from IMG folders using VFF/ESE and feeds this to RAWS on Exchange Server
5. RAWS on Exchange Server uses MAPI to write data back to the Exchange database much as if it were from a legacy type backup

Again, the things to note here are the differences between the backup to disk method versus the backup to tape method for backups and restores.

1. On backup, the backup to disk folders do not need to write catalog selections for the Exchange data following the backup. The restore selections are generated dynamically from the IMG folders which contain the complete Exchange IS database in it's native format. This is read by BE using the VFF (EDBProv.dll) and the ESE.dll provided from the Exchange server.

2. With the backup to tape, on the other hand, the granular restore selections must be gathered and written to a regular catalog to be browsed by the user when creating restore selections. This is accomplished by RAWS using MAPI on the Exchange server to gather the data from the Exchange server using Active Directory.

3. The restore process itself (aside from the initial restore selection creation) is essentially the same, other than, if the data is coming from tape, it has to be dumped to the staging area on disk first prior to the extraction of items and the restoration process.

4. Public Folder granular restore data will NOT show up in restore selections if the backup job is written to tape. This is a limitation of MAPI. We are not able to get enough information from Active Directory to associate the Public Folder data with its actual location. This is not a problem with restore selections from backup to disk folders due to the dynamic way we can read the Exchange database using the VFF technology.

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T. William's picture

When restoring from GRT backups of Exchange, be aware that there are two different places to specify where temp files will be put.
Using Tools->Options, one is on the "Restore" page, the other is on the "Microsoft Exchange" page.
In the restore job, one is on the "Advanced" page, the other is on the "Microsoft Exchange" page.
The Restore or Advanced page allows you to specify the directory local to the media server that will be used for "unpacking" if needed.
The Microsoft Exchange page allows to specify the directory on the Exchange server that will be used.

(I made the mistake of overlooking the local directory setting, and there was not enough space on the partition it specified as a default.)
 

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